When and Where in the U.S. Does the Summer Heat Reach its Peak?

By: Christopher C. Burt , 8:12 PM GMT on August 06, 2013

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When and Where in the U.S. Does the Summer Heat Reach its Peak?

Mike Seidel of The Weather Channel shared an interesting story with me concerning just which week of the summer is the hottest for various regions of the United States. Here’s a brief recap of that.

Environmental scientist Brian Brettschneider (of SWCA Environmental Studies in Anchorage, Alaska) produced a fascinating map of the U.S. illustrating which week of the summer normally proves to be the hottest.



Map of which week is normally the warmest for a typical summer in the U.S. Brian explains, “The map is based upon data from 7,800 stations across the country, using their 1981-2010 climate normals. If a number of days have the same peak value, the selected date is the middle of those dates. For Bush Intercontinental Airport, the official weather station of Houston, the dates of peak temperatures are August 7th – August 11th (85.1 F). The midpoint of those dates is August 9th.” Map courtesy of Brian Brettschneider.

Of special interest is the contrast across the state of Texas.



A close up of Texas where the peak of the heat ranges from June in the far western region to mid August in the southeastern portion of the state.

Brian explains the anomaly here,

“First, the water temperature in the southern Gulf of Mexico is generally warmer than the northern Gulf of Mexico, which means the air temperature near the water will retain its heat for a longer duration after the solar angle starts decreasing. Since the prevailing wind during summer is from the southeast, you will also notice a NE-SW orientation to the isolines. It is also possible that the northern Gulf experiences more sea breeze cloudiness later in the summer, which will bring the afternoon temperature down a little. I am not sure why the area along the Neches River is earlier than other areas nearby.”

I would propose that the reason for the peak of the heat occurring in June in western Texas is a result of maximum diurnal radiation occurring at that time, and also that June is usually a very dry month whereas in July monsoon moisture begins to flow into the Southwest (including extreme western Texas) thus inhibiting maximum afternoon temperatures due to increased cloud cover.


El Paso, Texas normally experiences its hottest temperatures of the year in June. The average daily maximum temperature in June is 96.5° versus 96.1° in July and 93.5° in August.

It is also interesting to see how late in the summer the ‘heat peak’ occurs in coastal California and Oregon. In fact, September is normally the warmest month of the year along the immediate West Coast when the prevailing wind begins to flow offshore inhibiting the cool marine layer that normally penetrates inland several miles during June through August.

How does all this correlate to extreme maximum temperature records?

Indeed, if we look at all-time record high temperatures we see that they have occurred in June for most locations in southern New Mexico, southern Arizona, and western Texas with some of these locations even experiencing their warmest single month on record in June as well:

El Paso, Texas: 114° on June 30, 1994. Warmest month on record: 89.0° June 1994.

Midland, Texas: 116° on June 27, 1994. Warmest month on record: 88.0° June 2011.

Roswell, New Mexico: 114° on June 27, 1994. Warmest month on record: 85.4° July 1980.

Tucson, Arizona: 117° on June 26, 1990. Warmest month on record: 90.6° July 2005.

Conversely, the hottest temperatures at many locations of eastern Texas have occurred in September (but no sites have had September as their warmest month on record):

Austin, Texas: 112° on September 5, 2000 (and August 28, 2011)

San Antonio, Texas: 111° on September 5, 2011

Corpus Christi, Texas: 109° on September 5, 2000

Houston, Texas: 109° on September 4, 2000 (and also on August 27, 2011).



Cool marine air and near perpetual fog from June through August keep much of coastal California and Oregon from measuring warm summer temperatures. September, when the prevailing winds begin to flow offshore, result in that being the warmest month of the year for these locations. Photo by Scott Sawyer.

Looking at the hottest temperatures at many coastal locations of California we see these also have occurred in September (or even October!):

San Diego, California: 111° on September 15, 1963. Warmest month on record: 78.9° September 1984.

Burbank, California 113° on September 12, 1971. Warmest month on record: 82.0° July 2006.

Eureka, California: 87° on October 26, 1993. Warmest month on record: 62.2° September 1979.

Bandon, Oregon: 100° on September 21, 1990. Warmest month on record: 62.3° August 1997.

San Francisco, California’s warmest month on record was September 1984 with a 69.4° average. Ditto for Los Angeles with an average of 81.3° that same month.

KUDOS: To Brian Brettschneider (of SWCA Environmental Studies, Anchorage, Alaska) for the maps and Mike Seidel at TWC for bringing this to my attention.

Christopher C. Burt
Weather Historian

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36. KatherineOK
6:50 PM GMT on August 23, 2013
I understand the average and peak temperatures are rising. I understand there are also wildfires in Siberia. However, looking at the map of fires in California and Colorado, I'm a little suspicious of their regular spacing. What if, under the guise of climate change related events, someone or some group of someones are actually setting some of these fires, to punish states that voted democratic, to punish Colorado for anti-gun stance, or even just greed, to open up public lands now damaged from fire to "development." I know the priority is to contain the fires. I don't know what capacity our fire fighting agencies have to investigate causes. They say lightning, but lightning would be more random than the map of these fires appear. Just wondering . . .
Member Since: August 23, 2013 Posts: 0 Comments: 0
34. 1900hurricane
10:38 PM GMT on August 08, 2013
Being from SETX and living here my entire life, I guess I didn't realize how much later we encounter our average hottest conditions than most other places around the country. Definitely an interesting piece of information!
Quoting 14. bappit:

Foehn conditions in Brownsville are entirely possible.

Here's the story from an event in April 2011: "July in April: 2011 Breaks Records"

"Four days were notable for the combination of desert–like "blast furnace" heat, each associated with rapid heating and drying forced by compressed air moving from higher terrain of West Texas and northern Mexico to the lower elevations of the Rio Grande Valley and South Texas Plains."

Similar type conditions occurred earlier this spring, which combined with the powerful cold fronts dropping south, lead to some crazy temp contrasts!

Member Since: August 2, 2006 Posts: 46 Comments: 11666
33. 1900hurricane
10:29 PM GMT on August 08, 2013
Quoting 3. Neapolitan:
Los Angeles saw its all-time hottest temperature ever in late September of 2010 (http://articles.latimes.com/2010/sep/27/local/la- me-hottest-ever-20100928), which fits into everything you've said here.

The wide variation in peak heat times across Texas is pretty fascinating, despite the fact that it's such a large state. That's something of which I was not aware...

I've long known about the June heat peak out in west Texas, but I thought it was just a unique feature about the area. I had never thought about contrasting it with the rest of the state, especially since I didn't realize that my portion of Texas has quite a late date of average peak heat.
Member Since: August 2, 2006 Posts: 46 Comments: 11666
32. 1900hurricane
10:26 PM GMT on August 08, 2013
Being from SETX and living here my entire life, I guess I didn't realize how much later we encounter our average hottest conditions than most other places around the country. Definitely an interesting piece of information!
Member Since: August 2, 2006 Posts: 46 Comments: 11666
31. bappit
10:00 PM GMT on August 08, 2013
Brian, thanks for the WU weather data link. I'm having fun looking at the other record high dates for that time of year--though a lot of records were set before the WU data starts. Seems like all the record highs were just before a wind shift.

April 4, 2011 101F Wind shift about the time of max temp.

April 3, 1974 99F Wind shift from south to north with a short period of west winds as they became northerly. Dewpoint drops as the wind starts to become westerly.

March 30, 1989 100F No wind shift. Winds were SW for a short while, but mostly southerly.

March 27, 1987 106F Wind shift occurred just after midnight the next morning. Became N to NNW.

March 21, 1955 95F Winds became westerly and then NW for most of day. Winds became NNE around 6PM. Some really low dewpoints prior to the wind shift. Temp was over 90F most of the day.

March 20, 2006 97F Wind shift from south-calm-NE while temp climbed until NE winds kicked in.
Member Since: May 18, 2006 Posts: 10 Comments: 5961
30. WunderAlertBot (Admin)
9:50 PM GMT on August 08, 2013
weatherhistorian has created a new entry.
29. bappit
9:14 PM GMT on August 08, 2013
Quoting 15. BaltimoreBrian:
Thanks bappit! I'm glad you confirmed my idea that foehn effects can happen in the lower Rio Grande valley.

I looked at the WU web page for Brownsville on April 4, 2011 (one of four dates the Brownsville NWS singled out in their article), and it looks a bit different from the March 27, 1984 record temp.

First I'd point out that the two dates are not that far apart on the calendar, so that suggests the 106ºF is not such a fluke. April 4, 2011 reached 101ºF, and March 27 was 5ºF warmer.

The main difference I see is the wind direction with 106ºF coming with a west wind at the surface. The 101ºF occurred with a south wind prior to the max temp with the wind shifting to the north at about the time of the max. Also, the temp on March 27 climbed steadily for several hours and held near the max for about two hours. The temp on April 4 rose about 10ºF in one hour prior to the maximum and the wind shift. Perhaps the wind shift pushed in air from a foehn wind and the foehn wind itself did not reach Brownsville proper unlike the March 27 event.
Member Since: May 18, 2006 Posts: 10 Comments: 5961
28. georgevandenberghe
8:06 PM GMT on August 08, 2013
Quoting 26. georgevandenberghe:
Quoting 17. weatherhistorian:



Yes, the 40.8%uFFFDC in Shanghai is confirmed. Not only Shanghai but most every other location in eastern China on Aug. 7th: Hangzhou hit 41%uFFFDC for the first time ever--their 9th day this summer that temps have hit 40%uFFFDC . Only TWO previous occasions in their entire POR (since 1958) have ever reached 40%uFFFDC prior to this summer. I'll have a blog update on this extraordinary heat wave in China (and also the latest in Europe where numerous all-time records were broken today in Croatia, Slovenia, San Marino, and Austria. I would have blogged about these today but tomorrow, August 8th, could even trump what has happened today at all these locations.


********* end weatherhistorian quote ****************

Okay, WHY is is so hot in China this summer? What synoptic pattern produces excessive heat there?

I noticed the GFS forecast has a closed contour of 582DM 1000-500mb thickness covering most of China. I don't know
what the midsummer mean is there but suspect it's less than 582DM. In the DC area which has similar (well okay a little cooler) mean summer temperatures the mean is 574DM (not fact checked but that's what I think it is interpoating from a mean chart I saw in a 1980 climate class). The Tibetian Plateau is a high level heat source and that may raise the mean value for China as the Rockies do for the Great Plains.

That closed contour persists for the two week forecast I looked at
initialized 12Z 8/7/2013.







Well I dug up a thickness climatology from the following paper which by the way makes an interesting read

https://ams.confex.com/ams/pdfpapers/47385.pdf

It differs slightly from my 1980 remembered figure but shows most of China does exceed 576DM mean thickness during July. There is a small closed +582DM contour over Central China which is higher than the mean anywhere in North America.

Member Since: February 1, 2012 Posts: 17 Comments: 1630
27. bappit
5:24 PM GMT on August 08, 2013
Quoting 24. DrBrianB:
[...] A couple of people have taken the idea from the paper (without citation) and made a name for themselves whenever a tropical system forms way out in the Atlantic. [...]

I'll complain for you.

Weasels!

People should be called out on plagiarism. Maybe it happens out of laziness or ignorance. Too often it gives the plagiarist an air of authority that they do not deserve. When your fellow WUBA's post information without a source, call them on it!

Edit: People can be naive about plagiarism. That's why my college made a point of educating people about it. Do it, and they'd kick you out of school. But they did warn the students because people can be naive.
Member Since: May 18, 2006 Posts: 10 Comments: 5961
26. georgevandenberghe
4:53 PM GMT on August 08, 2013
Quoting 17. weatherhistorian:



Yes, the 40.8%uFFFDC in Shanghai is confirmed. Not only Shanghai but most every other location in eastern China on Aug. 7th: Hangzhou hit 41%uFFFDC for the first time ever--their 9th day this summer that temps have hit 40%uFFFDC . Only TWO previous occasions in their entire POR (since 1958) have ever reached 40%uFFFDC prior to this summer. I'll have a blog update on this extraordinary heat wave in China (and also the latest in Europe where numerous all-time records were broken today in Croatia, Slovenia, San Marino, and Austria. I would have blogged about these today but tomorrow, August 8th, could even trump what has happened today at all these locations.


********* end weatherhistorian quote ****************

Okay, WHY is is so hot in China this summer? What synoptic pattern produces excessive heat there?

I noticed the GFS forecast has a closed contour of 582DM 1000-500mb thickness covering most of China. I don't know
what the midsummer mean is there but suspect it's less than 582DM. In the DC area which has similar (well okay a little cooler) mean summer temperatures the mean is 574DM (not fact checked but that's what I think it is interpoating from a mean chart I saw in a 1980 climate class). The Tibetian Plateau is a high level heat source and that may raise the mean value for China as the Rockies do for the Great Plains.

That closed contour persists for the two week forecast I looked at
initialized 12Z 8/7/2013.



Member Since: February 1, 2012 Posts: 17 Comments: 1630
25. blairtrewin
3:46 PM GMT on August 08, 2013
Quoting 17. weatherhistorian:


Yes, the 40.8�C in Shanghai is confirmed. Not only Shanghai but most every other location in eastern China on Aug. 7th: Hangzhou hit 41�C for the first time ever--their 9th day this summer that temps have hit 40�C . Only TWO previous occasions in their entire POR (since 1958) have ever reached 40�C prior to this summer. I'll have a blog update on this extraordinary heat wave in China (and also the latest in Europe where numerous all-time records were broken today in Croatia, Slovenia, San Marino, and Austria. I would have blogged about these today but tomorrow, August 8th, could even trump what has happened today at all these locations.


And indeed it has - 40 has been recorded in Austria for the first time ever (highest so far is 40.6). Details (in German) at the ZAMG (Austrian national meteorological service) site.
Member Since: October 25, 2010 Posts: 0 Comments: 33
24. DrBrianB
3:07 PM GMT on August 08, 2013
Thanks for the interest in the map. Perhaps my previous statement that few people are interested in the content of my maps came across the wrong way. It was sort of an inside joke. There's a core group of folks that finds this kind of stuff very interesting for which I am appreciative. A few months ago I posted the summer midpoint map to the NWS Facebook page and it got 0 Likes and 0 Comments which I thought was kind of interesting. Anyway, here is the same map but for the winter midpoint. Anyone is free to distribute is as long as they cite the author. Click on the image for a high resolution version.



Here is the link to the Summer map Chris blogged about: CLICK HERE FOR MAP.

Since I have a few people's attention. For whomever is interested, I wrote an article a few years ago tracking the origin region of landfalling tropical systems. Here is the link: http://journals.ametsoc.org/doi/abs/10.1175/2007J AMC1711.1

A couple of people have taken the idea from the paper (without citation) and made a name for themselves whenever a tropical system forms way out in the Atlantic. Dr. Masters occasionally links to at least one of their sites. I'm not complaining, just wanted to provide a little history. Have a great day!
Member Since: August 8, 2013 Posts: 0 Comments: 4
23. Neapolitan
2:58 PM GMT on August 08, 2013
Quoting 19. weatherhistorian:
I wish I had this information when I wrote my book on extreme weather!
Well, then, that's even more reason to look forward to your revised and updated edition. ;-)
Quoting 18. DrBrianB:
Chris, I am the author of the maps you discussed in the blog post. I am happy to provide a more detailed methodology, an Excel file with the dates for all 7,000+ climate normal sites, and a companion map showing the winter climatological midpoint dates. That one is even more interesting in my opinion. Often when I make these types of maps I found that it is a very small group of people who find it interesting - often no one. It good to see that this map might be an exception to that rule.

- Brian Brettschneider (Anchorage, AK)
I'm with everyone else here in saying how much I appreciate your maps, and the work that went into producing them. Also, as a guy who dabbles from time to time in my own visualizations, I'd be very interested in seeing the full spreadsheet of which you wrote.

Out of curiosity--and forgive me if this has been addressed and I somehow missed it--have the midpoint dates for any locations shifted over the long term?
Member Since: November 8, 2009 Posts: 4 Comments: 13470
21. TomTaylor
8:24 AM GMT on August 08, 2013
Quoting 18. DrBrianB:
Chris, I am the author of the maps you discussed in the blog post. I am happy to provide a more detailed methodology, an Excel file with the dates for all 7,000+ climate normal sites, and a companion map showing the winter climatological midpoint dates. That one is even more interesting in my opinion. Often when I make these types of maps I found that it is a very small group of people who find it interesting - often no one. It good to see that this map might be an exception to that rule.

- Brian Brettschneider (Anchorage, AK)
Welcome to Wunderground, Brian.

Just wanted to say I would have to disagree with what you say about your maps. I think all of us appreciate the time and effort you put into those maps. Personally, I love when individuals make the effort to code and plot new weather visualizations. The science of meteorology involves an insane amount of data. How we visualize this data is critical to how we interpret the information. Please keep up the good work...
Member Since: August 24, 2010 Posts: 19 Comments: 4357
20. cat7hurricane
8:11 AM GMT on August 08, 2013
Quoting 18. DrBrianB:
Chris, I am the author of the maps you discussed in the blog post. I am happy to provide a more detailed methodology, an Excel file with the dates for all 7,000+ climate normal sites, and a companion map showing the winter climatological midpoint dates. That one is even more interesting in my opinion. Often when I make these types of maps I found that it is a very small group of people who find it interesting - often no one. It good to see that this map might be an exception to that rule.

- Brian Brettschneider (Anchorage, AK)
Welcome!

Great work on the maps
Member Since: April 7, 2011 Posts: 0 Comments: 27
19. Christopher C. Burt , Weather Historian
7:04 AM GMT on August 08, 2013
Quoting 18. DrBrianB:
Chris, I am the author of the maps you discussed in the blog post. I am happy to provide a more detailed methodology, an Excel file with the dates for all 7,000+ climate normal sites, and a companion map showing the winter climatological midpoint dates. That one is even more interesting in my opinion. Often when I make these types of maps I found that it is a very small group of people who find it interesting - often no one. It good to see that this map might be an exception to that rule.

- Brian Brettschneider (Anchorage, AK)


Thanks for this Brian, and if it is any consolation, I think A LOT of people are impressed with your research on this and look forward to seeing your winter map as well. I wish I had this information when I wrote my book on extreme weather!
Member Since: February 15, 2006 Posts: 291 Comments: 277
18. DrBrianB
5:27 AM GMT on August 08, 2013
Chris, I am the author of the maps you discussed in the blog post. I am happy to provide a more detailed methodology, an Excel file with the dates for all 7,000+ climate normal sites, and a companion map showing the winter climatological midpoint dates. That one is even more interesting in my opinion. Often when I make these types of maps I found that it is a very small group of people who find it interesting - often no one. It good to see that this map might be an exception to that rule.

- Brian Brettschneider (Anchorage, AK)
Member Since: August 8, 2013 Posts: 0 Comments: 4
17. Christopher C. Burt , Weather Historian
3:48 AM GMT on August 08, 2013
Quoting 16. BaltimoreBrian:
'It's Too Hot': Shanghai Wilts In Record-Setting Heat Wave (courtesy of Barbamz's blog)

40.8C will be a new record if confirmed. Those poor people!


Yes, the 40.8C in Shanghai is confirmed. Not only Shanghai but most every other location in eastern China on Aug. 7th: Hangzhou hit 41C for the first time ever--their 9th day this summer that temps have hit 40C . Only TWO previous occasions in their entire POR (since 1958) have ever reached 40C prior to this summer. I'll have a blog update on this extraordinary heat wave in China (and also the latest in Europe where numerous all-time records were broken today in Croatia, Slovenia, San Marino, and Austria. I would have blogged about these today but tomorrow, August 8th, could even trump what has happened today at all these locations.
Member Since: February 15, 2006 Posts: 291 Comments: 277
16. BaltimoreBrian
2:05 AM GMT on August 08, 2013
'It's Too Hot': Shanghai Wilts In Record-Setting Heat Wave (courtesy of Barbamz's blog)

40.8C will be a new record if confirmed. Those poor people!
Member Since: August 9, 2011 Posts: 26 Comments: 8558
15. BaltimoreBrian
1:48 AM GMT on August 08, 2013
Thanks bappit! I'm glad you confirmed my idea that foehn effects can happen in the lower Rio Grande valley.
Member Since: August 9, 2011 Posts: 26 Comments: 8558
14. bappit
12:53 AM GMT on August 08, 2013
Quoting 12. weatherdogg:

I don't think the terrain W of Brownsville would support that. You have to go a fair distance before you get any significant elevation.

Foehn conditions in Brownsville are entirely possible.

Here's the story from an event in April 2011: "July in April: 2011 Breaks Records"

"Four days were notable for the combination of desert–like "blast furnace" heat, each associated with rapid heating and drying forced by compressed air moving from higher terrain of West Texas and northern Mexico to the lower elevations of the Rio Grande Valley and South Texas Plains."
Member Since: May 18, 2006 Posts: 10 Comments: 5961
13. georgevandenberghe
8:20 PM GMT on August 07, 2013
Quoting 7. weatherhistorian:



Thanks for this BaltimoreBrian!

Indeed Eureka has such a narrow cone of extreme temperatures that it doesn't surprise me that among their record high min's winter events would show up. When a so-called 'pineapple express' sets up mild air makes its way to the west coast (when a mild wet atmospheric stream is in play). I know even here in Oakland, we occasionally have very mild nights in the winter, sometimes much warmer than our summer nights. As my friends know I often winge about how awful the summers in the Bay Area are--in fact that is what is happening now--I'll take a typical winter day over a typical summer day anytime in this neck of the woods. Summers are nasty around here (at least west of the East Bay hill ridge). Pure misery.

The Brownsville record is really interesting, although an outlier, I suspect that record will be broken sooner than later one of these days.



I always remember Mark Twain's quote

"The coldest winter I ever experienced was the summer I spent in San Francisco"


I was born in the bay area but my house was destroyed in a mudslide and my parents left when I was only a few months old so no memories.

As an adult I remember participating in a conference at Berkeley in 2002, flying out of 90s in DC in August and experiencing the combination of decent afternoon August sun and only about 60F the next day
along the Bay. It felt REALLY good!
Member Since: February 1, 2012 Posts: 17 Comments: 1630
12. weatherdogg
6:38 PM GMT on August 07, 2013
Quoting 10. BaltimoreBrian:
Brownsville on March 27 1984 had very low pressure and winds out of the W when the temp spiked. A foehn?

I don't think the terrain W of Brownsville would support that. You have to go a fair distance before you get any significant elevation.

Quoting 7. weatherhistorian:



Thanks for this BaltimoreBrian!

Indeed Eureka has such a narrow cone of extreme temperatures that it doesn't surprise me that among their record high min's winter events would show up. When a so-called 'pineapple express' sets up mild air makes its way to the west coast (when a mild wet atmospheric stream is in play).

I think that is partly correct. In contrast to Brownsville, Eureka does have quite high terrain nearby, in this case to its NE. I suspect the high overnight lows in Jan/Feb are due to foehn like conditions there when a system comes in from the SW and pulls air downslope from the ENE. Another area that has similar conditions is the so-called Banana Belt on the Oregon coast. I bet Brookings would have similar stats.
Member Since: September 5, 2005 Posts: 0 Comments: 88
11. 24hourprof
4:11 PM GMT on August 07, 2013
Hi Chris,

Thanks for posting this. I agree completely with what you wrote about west Texas. The proof is in the pudding, and here are the relevant numbers for El Paso, Texas (these are the normals, means, and extremes from the most recent annual Local Climate Data):

Member Since: October 24, 2012 Posts: 90 Comments: 798
10. BaltimoreBrian
4:41 AM GMT on August 07, 2013
Brownsville on March 27 1984 had very low pressure and winds out of the W when the temp spiked. A foehn?
Member Since: August 9, 2011 Posts: 26 Comments: 8558
9. BaltimoreBrian
1:28 AM GMT on August 07, 2013
Late March 1984 was a weird time. March 28th there was a severe tornado outbreak in North/South Carolina that killed dozens. A very deep storm was in the northeast.
Member Since: August 9, 2011 Posts: 26 Comments: 8558
8. BaltimoreBrian
1:25 AM GMT on August 07, 2013
Naples FL has their highest daily average high of 91.4 from July 19 to August 3 inclusive.

Naples' warmest average low temperature is 75.7 from August 28 to September 1 inclusive.
Member Since: August 9, 2011 Posts: 26 Comments: 8558
7. Christopher C. Burt , Weather Historian
1:25 AM GMT on August 07, 2013
Quoting 5. BaltimoreBrian:
My favorite is Eureka, CA. they had their all time record high on October 26, 1993.

Eureka's warmest low on record is 63. It has been recorded 4 times including February 26 1980 and January 18, 1981! (page 7)

I'm not aware of any other all-time heat record set in the lower 48 in January or February.

Brownsville TX set their all-time heat record in March 1984.




Thanks for this BaltimoreBrian!

Indeed Eureka has such a narrow cone of extreme temperatures that it doesn't surprise me that among their record high min's winter events would show up. When a so-called 'pineapple express' sets up mild air makes its way to the west coast (when a mild wet atmospheric stream is in play). I know even here in Oakland, we occasionally have very mild nights in the winter, sometimes much warmer than our summer nights. As my friends know I often winge about how awful the summers in the Bay Area are--in fact that is what is happening now--I'll take a typical winter day over a typical summer day anytime in this neck of the woods. Summers are nasty around here (at least west of the East Bay hill ridge). Pure misery.

The Brownsville record is really interesting, although an outlier, I suspect that record will be broken sooner than later one of these days.
Member Since: February 15, 2006 Posts: 291 Comments: 277
6. BaltimoreBrian
1:21 AM GMT on August 07, 2013
You can find daily average temps to the 10th of a degree on this site.

Dallas-Fort Worth has its highest daily average maximum of 97.0 from August 2-10, inclusive. The warmest average daily low is 75.9 from August 2-9 inclusive.

So August 2-9 seems like the hottest time there! As in NOW.
Member Since: August 9, 2011 Posts: 26 Comments: 8558
5. BaltimoreBrian
1:02 AM GMT on August 07, 2013
My favorite is Eureka, CA. they had their all time record high on October 26, 1993.

Eureka's warmest low on record is 63. It has been recorded 4 times including February 26 1980 and January 18, 1981! (page 7)

Eureka used to have an all time record high of 85 set on February 17, 1930 (tied with 5 other dates) This was not broken until September 20, 1983 when it reached 86.

I'm not aware of any other all-time heat record set in the lower 48 in January or February.

Brownsville TX set their all-time heat record on March 27, 1984.

Member Since: August 9, 2011 Posts: 26 Comments: 8558
4. zampaz
10:14 PM GMT on August 06, 2013
Appreciate you sharing this.
It will be interesting to see how temperature trend patterns change over the next 30 years.
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3. Neapolitan
9:37 PM GMT on August 06, 2013
Los Angeles saw its all-time hottest temperature ever in late September of 2010 (http://articles.latimes.com/2010/sep/27/local/la- me-hottest-ever-20100928), which fits into everything you've said here.

The wide variation in peak heat times across Texas is pretty fascinating, despite the fact that it's such a large state. That's something of which I was not aware...
Member Since: November 8, 2009 Posts: 4 Comments: 13470
2. maxcrc
9:16 PM GMT on August 06, 2013
Oh Mr. Brian come on ! You don't even know the climates and microclimates of your own country ?

Southern Texas in affected by the Tropical season in Mexico which has its peak before the summer solstice

1-The maximum sun irradiation inside the Tropics is before the Solstice and match when the sun is at the zenital point. The zenit exactly match with the Summer Solstice on the tropic lines.

2-The tropical rainy season start developing also near the zenital point of the sun according to the movement of the ITCZ.

Therefore Southern Texas is affected by the hot and dry air in the peak of the tropical dry season.

In the peak of summer there is more moisture in the atmosphere which generally prevents extreme peaks in temperatures.
So, while the inner southern Texas has its thermal peak before summer, the coastal southern Texas might have its peak at the end of summer because the sea effect. But in the latter case it depends on the year, the peak might occur sometimes before summer.
In both cases, generally it doesn't occur in the middle of the summer because the influence of the tropical season.

Coastal California is another story, with the strong oceanic effect

1-The ocean very slowly sucks the heat and tend to be warmer in late summer ,early fall.
2-Winds generally turn from inland to the coast during the October seasonal change causing sudden temperature peaks along the coast.

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1. SPLbeater
8:31 PM GMT on August 06, 2013
If this is true, my area peaked almost a month ago here in North Carolina...and if this is true, it's been a cool summer. We aint hit 100 yet.
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About weatherhistorian

Christopher C. Burt is the author of 'Extreme Weather; A Guide and Record Book'. He studied meteorology at the Univ. of Wisconsin-Madison.