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All-time Heat Record tied at Hilo, Hawaii on Thanksgiving?

By: Christopher C. Burt, 8:32 PM GMT on December 02, 2013

All-time Heat Record tied at Hilo, Hawaii on Thanksgiving?

According to the NWS-Honolulu office the temperature spiked to 94°F (34.4°C) on the morning of November 28th tying Hilo’s all-time maximum temperature for any month. However, it is an anomalous figure and hard to believe (as is the ‘official’ Hawaiian state record high of 100°F (37.8°C) set at Pahala in April 1931. Here are the details.

According to the METARS data at Hilo International Airport a temperature of 94°F was achieved at the site sometime between 10 a.m.-11:00 a.m. on Thanksgiving Day last week (November 28th) tying the previous all-time heat record for the site last set on May 20, 1966. The morning low was 68°. Records at the airport date back to 1946 although weather records have been maintained at other locations in the city since 1905. The previous warmest November day at Hilo was 92° on November 7, 1996 and a 93° reading was achieved on December 14, 1980, so we know that the 94° figure last week is within the realm of possibility despite the fact that November is not normally one of the city’s warmest months. The normal temperature range for Hilo on November 28 is 66°-80°.



Monthly climate summary for Hilo this past November. The 94° temperature is noted as a new monthly record for the site (and would also tie the all-time record for any month). NWS-Honolulu.

On Thursday morning the wind had been blowing lightly from the SW until about 11 a.m. when it switched to the SE, in other words from offshore to onshore. However, down sloping extreme heat events are not common in Hawaii if, in fact, they ever occur to the extent as reported at Hilo.



A map of the Hilo area showing the location of the airport where the 94° reading was apparently measured. Note that the airport is very near the coastline.

Also of note is that the previous day (Wednesday November 27th) a daily record high of 88° was measured (former record 86° in 1977) and a record event report was issued by NWS-Honolulu. Strangely, however, no record event report was issued for the more incredible 94° ‘record’ set the following day. I have requested verification from the office concerning this rather significant event and will let you know their response when I hear back. If verified, it would be the only instance of an all-time record high being set for a significant weather station during the month of November anywhere in the U.S.

Trouble with Hawaiian Temperature Records

This would not be the first anomalous heat record set in Hawaii. In fact, the ‘official’ state maximum temperature record of 100° reportedly set at Pahala, Big Island, on April 27, 1931 is most certainly bogus. As one can see in the COOP form below the maximum temperature for Pahala on that day was missing and replaced with the figures 9999, meaning missing data not 100°! Amazingly, the record still seems to be widely cited (including in the NCDC state extremes data archive).




A digitized copy of the COOP report for Pahala, Big Island, Hawaii for April 1931. The original COOP report is not in the NCDC online archives since the reports for 1929-1945 are missing. Table above retrieved from the Utah State University GIS Climate Center archives.

So if the 100° figure at Pahala is bogus what IS the record high for Hawaii? Climatologist and temperature detective Maximiliano Herrera posits that the warmest reliably measured temperature ever measured in the state is 97° at Kahalui, Maui on August 31, 1994. There have been numerous other reports of 98° temperatures most of which can be dismissed. The most possibly reliable one being that reported at Puunene, Maui on August 19, 1951 and again on July 14, 1957.

KUDOS: Thanks to Trent McCotter for bringing the Hilo temperature event to my attention.

Christopher C. Burt
Weather Historian

Extreme Weather Heat

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Reader Comments

I'm surprised there aren't more high temperature readings on the west side of the big island of Hawaii with downsloping from trade winds and heat released from condensation in showers on the east side of the island.

I checked the hourly readings and Hilo did get off to an abnormally warm start that morning. Sooooo...I'm just not sure.
I find it particularly odd that the "record" high occurred at 10am based on the hourly airport readings. By 11am, temps were back into the low 80s. Seems highly unlikely, although in theory there could have been a very short period of gusty westerly downslope winds that did this. The gap there along route 123 rises to over 7,000' if I recall correctly.
The hourly record in Donnie's link does show a wind shift from the SW to the SE in the late morning. Whether the temperature really did rise to 94 I can't say--wasn't there!
It only got up to 88 where I am-3 miles from downtown-and though I can't actually say if it was really 94 that day, I can definitely assure you that it was the hottest day we've had in at least a month.
Quoting 2. weatherdogg:
I find it particularly odd that the "record" high occurred at 10am based on the hourly airport readings. By 11am, temps were back into the low 80s. Seems highly unlikely, although in theory there could have been a very short period of gusty westerly downslope winds that did this. The gap there along route 123 rises to over 7,000' if I recall correctly.


I am also very skeptical.
The dew point didnt move a bit, nothing, this would dismiss a case of downslope winds. Dew point must have dropped, but it didnt move during the rising (supposed) of the temperature.
Also there was nothing unusual that day in terms of wind direction, humidity rate, etc compared to other days. It looks like more a 88-90F than a 94F. Anyway, i hope we will get an answer from the observer.
Quoting 1. DonnieBwkGA:
I'm surprised there aren't more high temperature readings on the west side of the big island of Hawaii with downsloping from trade winds and heat released from condensation in showers on the east side of the island.

I checked the hourly readings and Hilo did get off to an abnormally warm start that morning. Sooooo...I'm just not sure.


The problem is that stations can´t be everywhere and can´t cover the whole territory.
I also think slightly higher temperatures might have ocurred in small areas affected by downslope winds.
Quoting 1. DonnieBwkGA:
I'm surprised there aren't more high temperature readings on the west side of the big island of Hawaii with downsloping from trade winds and heat released from condensation in showers on the east side of the island.

I checked the hourly readings and Hilo did get off to an abnormally warm start that morning. Sooooo...I'm just not sure.


due to the topography of the island the tradewinds are forced to go around the island and this causes an on-shore flow on the westside of the island.

here is the 10am weather discussion for hawaii on thanksgiving day. and the link to more previous discussions. hope this helps in some way. i think the sw flow is due to the ridge over head creating a land breeze then switching sea breeze once day time heating got going.

000
FXHW60 PHFO 282028
AFDHFO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
1025 AM HST THU NOV 28 2013

.SYNOPSIS...
A WEAK RIDGE OF HIGH PRESSURE OVER THE ISLANDS WILL KEEP WINDS LIGHT
TODAY. AN APPROACHING COLD FRONT WILL MOVE SLOWLY TOWARD THE
ISLANDS...TURNING OUR WINDS SOUTHERLY AND BRINGING AN INCREASE IN
DEEP TROPICAL MOISTURE AND INSTABILITY THIS WEEKEND. THE FRONT WILL
STALL NEAR KAUAI AND OAHU...BRINGING A THREAT FOR HEAVY SHOWERS OR
THUNDERSHOWERS TO THOSE ISLANDS OVER THE HOLIDAY WEEKEND.

&&

.DISCUSSION...
LIGHT WINDS OVER THE ISLANDS TODAY WILL ALLOW FOR SEA BREEZES TO
DEVELOP...BUT THE 12Z SOUNDINGS AND 1153Z MODIS PASS SHOWED THE
AIRMASS WAS ON THE DRY SIDE OF NORMAL OVER THE STATE...ALONG WITH A
CAPPING INVERSION SLOPING FROM NEAR 5500 FEET NEAR PHLI TO 7000 FEET
NEAR PHTO. EXPECTING PLENTY OF AFTERNOON CLOUDS BUT ONLY ISOLATED
SHOWERS OWING TO THE RELATIVELY DRY AND STABLE NATURE OF THE CURRENT
AIRMASS. THERE IS A SMALL CHANCE THAT A FEW SHOWERS COULD DEVELOP ON
THE CONVERGENCE ZONE TO THE LEE OF MOLOKAI AND PUSH NW TOWARD OAHU
THIS AFTERNOON...A SCENARIO SUPPORTED BY SOME OF THE HIGH RESOLUTION
GUIDANCE.

THE BACKGROUND FLOW FROM THE SE WILL BRING VOG UP OVER THE SMALLER
ISLANDS STARTING TODAY...AND THIS WILL PROBABLY CONTINUE INTO FRI.
WIND SPEEDS WILL INCREASE AS THE FRONT APPROACHES...AND THE
INCREASINGLY GUSTY WINDS WILL HELP TO DISPERSE THE VOG SOMEWHAT ON
FRIDAY.

AS A SLOW MOVING FRONT APPROACHES FROM THE NW...DEEP TROPICAL
MOISTURE WILL GRADUALLY START TO INCREASE TONIGHT. SHOWERS WILL
START TO FORM IN THE MESOSCALE CONVERGENCE ZONES TO THE LEE OF THE
ISLANDS...AS WELL AS IN ANY PREFRONTAL CONVERGENCE...AND A FEW OF
THESE COULD MOVE UP OVER THE WESTERN MAIN ISLANDS TONIGHT INTO FRI.

STARTING LATER FRIDAY...LOW LEVEL SYNOPTIC SCALE CONVERGENCE WILL
BEGIN TO INCREASE OVER THE ISLANDS...WITH INCREASINGLY UNSTABLE AIR
BEGINNING TO NUDGE IN FROM THE W. AS WAS DISCUSSED OVERNIGHT...THE
LATEST MODEL RUNS CONTINUE TO BE SLOWER WITH THE ARRIVAL OF THE
DEEPER MOISTURE AND INSTABILITY...SO WE WILL PROBABLY HAVE TO BACK
OFF ON THE CHANCE FOR HEAVY SHOWERS OR THUNDERSHOWERS FRIDAY NIGHT
FOR OAHU...BUT THIS STILL LOOKS OK FOR KAUAI.

ALTHOUGH THE FRONT WEAKENS AT FIRST AFTER IT ARRIVES...THE 00Z RUNS
OF THE GLOBAL MODELS...INCLUDING GFS...ECMWF...CANADIAN...AND
NAVEGEM ALL SHOWED A SIGNIFICANT CHANGE...SHOWING THE STALLED FRONT
BEING REINVIGORATED BY A RATHER STRONG UPPER LOW TO THE NW OF THE
ISLANDS BY SUNDAY WITH A SIZABLE NORTH TO SOUTH BAND OF DEEP
MOISTURE NEARLY STATIONARY AROUND KAUAI AND OAHU. THIS SCENARIO HAS
NOT BACKED OFF MUCH IN THE 12Z RUNS...AND SO ALTHOUGH THIS HEAVY
RAIN EVENT FOR KAUAI AND POSSIBLY OAHU NOW LOOKS TO START LATER THAN
PREVIOUSLY ENVISIONED...IT MIGHT STILL PAN OUT. LARGE UNCERTAINTY AS
TO THE TIMING AND MAGNITUDE OF THE THREAT NECESSITATE WAITING A
LITTLE LONGER FOR THE GUIDANCE TO LOCK IN BEFORE ISSUING A WATCH. IT
SHOULD BE NOTED THAT NONE OF THE GUIDANCE SUGGESTS MUCH OF A THREAT
AT ALL TO MAUI COUNTY OR THE BIG ISLAND AT THIS POINT.

THE MODEL SHOW A HEALTHY DOSE OF KONA WINDS AS WELL JUST AHEAD OF
THE FRONT...PICKING UP TO 15-20 KT SURFACE BACKGROUND FLOW. THE
UNIVERSITY OF HAWAII HIGH RESOLUTION GUIDANCE SHOWS 925 MB WINDS OF
35-40 KT IN THE DOWNSLOPE AREAS ON THE N SHORE OF KAUAI AND 30-35 KT
ON OAHU STARTING FRI NIGHT INTO SATURDAY. HAVE ADJUSTED THE WIND
GUST GRIDS IN THESE AREAS TO BE CLOSER TO THESE VALUES. LOOKS A BIT
SHY OF WIND ADVISORY CRITERIA FOR THOSE SPOTS BUT WILL HAVE TO KEEP
AN EYE ON THIS.

GUIDANCE SHOWS THE FRONT GRADUALLY WEAKENING EARLY NEXT WEEK AS THE
UPPER LEVEL LOW HELPING TO SUPPORT THE FRONT MOVES AWAY. WEAK
SURFACE RIDGING REBUILDS NEAR THE ISLANDS AND SO EXPECTING THINGS TO
STABILIZE DURING THAT TIME.

&&

.AVIATION...
VFR CONDITIONS ARE EXPECTED TO PERSIST THROUGH MUCH OF THE DAY WITH
LIGHT SOUTHEAST FLOW. CLOUDS WILL BUILD UP OVER THE HIGHER TERRAIN
TODAY...BUT ARE NOT EXPECTED TO REDUCE VISIBILITY. NO AIRMETS
EXPECTED THROUGH AT LEAST 04Z.

&&

.MARINE...
THE LARGE 310 DEGREE SWELL JUST ARRIVED AT BUOY 51101 AS OF 20Z.
SURF IS EXPECTED TO REACH THE UPPER END OF SURF ADVISORY CRITERIA
IN SOME SPOTS FOR N AND W FACING SHORES. A SMALL CRAFT ADVISORY HAS
BEEN ISSUED FOR THE AREA NEAR KAUAI IN ANTICIPATION OF SEAS AT THE
10 FT ADVISORY THRESHOLD. WILL WATCH THE BUOY CAREFULLY TO SEE IF
ADJUSTMENTS NEED TO BE MADE TO EITHER ADVISORY.

HIGH RESOLUTION GUIDANCE SUGGESTS THAT KONA WINDS WILL APPROACH THE
25 KT ADVISORY CRITERIA IN SOME OF THE NORMALLY WINDY AREAS AS THE
FRONT APPROACHES...PARTICULARLY IN THE KAULAKAHI CHANNEL. EVEN
THOUGH THE SWELL WILL DIMINISH OVER THE WEEKEND...WILL LIKELY NEED
TO EXPAND/EXTEND THE SCA TO COVER THESE AREAS. THE COMBINATION OF
KONA WINDS AND LINGERING NW SWELL WILL MAKE FOR ROUGH CONDITIONS
OVER THE WEEKEND.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF ADVISORY TONIGHT AND FRIDAY FOR N AND W FACING SHORES OF
NIIHAU...KAUAI...AND OAHU...AND FOR N FACING SHORES OF MOLOKAI AND
MAUI.

&&

$$
R BALLARD...DISCUSSION/MARINE
M BALLARD...AVIATION
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