WunderBlog Archive » Weather Extremes

Category 6 has moved! See the latest from Dr. Jeff Masters and Bob Henson here.

Some Errors in the NCDC U.S.A. State Weather Extreme Records Data: Part 1

By: Christopher C. Burt, 8:21 PM GMT on March 18, 2011

Some Errors in the NCDC U.S.A. State Weather Extreme Records Data: Part 1

Last year the National Climate Data Center (NCDC) created a new web site that neatly summarizes various state weather records: specifically what the extreme values for hottest and coldest temperatures, maximum 24-hour precipitation and 24-hour snowfall, and maximum recorded snow depth for each individual state are. This may be viewed at the NCDC web site.

The interactive map they provide and the consolidation of these records into a single user-friendly web site is a big improvement over the way they previously displayed this information (which was by listing separate tables and maps for each of the values in question). The NCDC also updated and revised the figures through the year 2009 using their collection of COOP station forms maintained in the NOAA database. These may be viewed here at the IPS web site.

Over the next few weeks I will post a series of blogs concerning mistakes, some obvious and others more subjective, that I and others have discovered in the course of fact-checking these records.

Some Errors with the Official State Records: Case of Hawaii

For some reason the extreme weather records for the state of Hawaii are fraught with errors. Both the ‘official’ record high temperature of 100° at Pahala, Big Island on April 27, 1931 AND the official low temperature of 12° at Mauna Kea Observatory on May 17, 1979 are obviously wrong.


Unfortunately, the COOP forms for Pahala have been digitized and the original form no longer appears on the IPS site mentioned above. However, the digitized version of the form is available for viewing at the excellent Utah State University Climate Center’s ‘Climate Database’ (see at the USU Climate Center's web site.)

Looking at the Pahala dataset for April 1931 we see that the maximum temperature for April 27 is, in fact, missing and represented with the figures “9999”, meaning missing data. For some reason this has been interpreted by the NCDC to mean 100°!

The digitized version of the Pahala, Hawaii COOP form for April 1931. Reproduced from the Utah State University Climate Center database.

We can see that the day before April 27th the maximum temperature was just 82°F and the day after just 80°F. Furthermore, the observation time temperature (likely made at 7a.m. local time) was a fairly normal 70° on April 27th. It is amazing that this bogus 100°F reading from Hawaii has been on the record books for some 80 years already!

So just what is the real record high temperature for the state of Hawaii? Unfortunately, this is very difficult to determine. No 99°F reading has ever been made but there have been six (6) different occasions that 98°F has been reported:

At Waianae, Oahu in July 1915

At Mahukona, Big Island on an undetermined date prior to 1941

At Kaanapali, Maui on an undetermined date prior to 1941

At Puunene, Maui on Aug. 19, 1951

At Puunene, Maui (again) on July 14, 1957

At Sea Mountain, Big Island on Sept. 1990

After extensive research and investigating the COOP forms (where available) for the above sites, it would seem the least suspicious figure from the above list is Puunene. The two 98°F readings from here were made at a small airport about 4 miles southeast of Kuhului on Maui. The inland and low elevation setting make this location a reasonable candidate for hot weather in the otherwise temperate Hawaiian Isles.

COOP form for Puunene, Maui for August 1951, one of the two months that the station reported 98°F temperatures.

Interestingly, this means that Hawaii is now the ‘coolest’ state in the Union so far as record high temperatures are concerned. Even Alaska has recorded a 100°F reading (at Fort Yukon on June 27, 1915).


The coldest temperatures on record for Hawaii are, of course, reported from the several mountaintop observatories in the state. Mauna Kea Observatory located near the summit of said mountain at 13,796’ has had a potted history of weather observations. I say potted because for some reason the COOP forms from this site have been stamped as “unreliable” for several years (1976-1978) of observations during the 1970s. This includes the month of January 1976 when a 9°F reading was made on January 12th of that month and a 12°F reading on Feb. 22, 1977. The ‘official’ low of 12°F on May 17th, 1979 is obviously an error when one looks at the COOP form for that month:

COOP form for the Mauna Kea Observatory in May 1979. A new minimum thermometer was installed on the 5th of the month.

One can see the observer has circled the 12°F reading and replaced it with a 21°F note and question mark (see above). Furthermore, the low temperatures on both the day before and after May 17th were just 23°F lending further doubt to the 12°F reading.

The summit of Mauna Kea in the winter of 1971 with snow down to about 11,000’ (3,350m). Photo by Dale P. Cruikshank.

So what might be the actual lowest temperature for Hawaii? A 14°F reading from the summit station at Haleakala, Maui (elevation 10,023’) on Jan. 2, 1961 is the 2nd coldest reading from the state. This, however, is also unbelievable since the low temperature from the previous and following days was just 34°. Twenty-degree swings in minimum temperatures from one day to the next are highly improbable in tropical environments like Hawaii. This leaves a 15°F reading from Mauna Kea Observatory on Jan. 5, 1975 as the mostly likely reliably measured temperature in the state on record.

Next week I will look at some other glaring errors from the ‘official’ records in some other states.

KUDOS: Maximiliano Herrera, Howard Rainford, and Trent McCotter.


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