Re-Cap of Summer of 2011 Heat Records in the U.S.A.

Re-Cap of Summer of 2011 Heat Records in the U.S.A.: Perhaps one of the Four Warmest Summers Since 1895

The final data has yet to be compiled by the NCDC but the climatological summer (June-August) of 2011 is on track to be one of the warmest, if not the warmest, on record for the contiguous United States. It has, however, without doubt been the warmest for the South Central and Southeast (excluding the Florida Peninsula) regions. Here is a factual list of all the major sites (meaning those with a long period of record and of some metropolitan significance) that have just endured their warmest summer and/or their hottest-single-month on record. A list of all-time absolute maximum temperatures recorded is also included.

An Interesting Fact

San Angelo and Lubbock, Texas both recorded their single hottest month on record in June. Then in July those records in turn were broken. And then, in August, their July records were broken! In other words, in over 100 years of records for both cities, their three hottest-single-months were respectively, August, July, and June 2011. I do not believe this has occurred at any American weather station in recorded history.

Many sites, especially in the Southeast, recorded their warmest summer on record in 2010 only to have it broken this past summer in 2011. Given the long periods of record of these sites, this quite an accomplishment.

Phenomena of Endurance of Heat and Exceptional Warm Nights

It should be noted that it was not the actual extreme maximums of the heat that has been so remarkable this past summer but the endurance of the heat and the phenomena of many record high minimum temperatures. In fact, I will post a blog later on this subject since it seems to be an enduring quality of recent heat waves over the past years and deserves special attention.

The Data

Below are lists of all the important sites that:

1) Recorded their warmest climatological summer

2) Recorded their single-warmest month on record

3) Recorded their absolute maximum temperature

This list only includes the 303 sites that I follow assiduously since they all meet the criteria of long periods of record (POR), represent important population centers, and/or represent an important climate region or climate type (thanks to their altitude or geographic location). The sites represent where 90% of the nation’s population resides within a 50 mile radius of each location..

Below is a map of the sites I mentioned above. I have shaded the region that has just recorded its warmest summer on record. This represents about 15% of the contiguous United States (45 of my 303 stations).



Here is the list of some 45 (out 303) stations that have recorded their warmest climatological summer on record during this past summer of 2011:



Here is a list of the sites that have recorded their warmest single month on record (36 of 303 stations) during the summer of 2011. This may have been either during June, July, or August:



Here is a list of the sites that have either tied or broken their all-time absolute maximum temperatures during the summer of 2011:



Conclusion

So many heat records of various types have been shattered this past summer that it is impossible to quantify them. Many have to do with longest consecutive days with 100°+ or 90°+ temperatures or the aggregate of such. Suffice it to say that almost every site in Texas and Oklahoma broke such as well as portions of Arkansas and Louisiana. Furthermore, I have not mentioned the dozens of sites (from my list of 303 stations) that reported their 2nd warmest summer or 2nd warmest single month this past summer.

Not since the great heat waves of 1934 and 1936 has the United States seen so many heat-related records broken as occurred this past summer (not to mention last summer, 2010). The back-to-back nature of the intensity of the past two summers should raise some interesting questions, questions I am not qualified to address.

Later this month (around September 15th) we will have the final NOAA evaluation of this summer’s warmth relative to those past. The three warmest summers in the contiguous United States records (since 1895) were : 1) 1936 with a 74.6° nation-wide average, 2) 2006 with a 74.4° average and 3) 1934 with a 74.2° average. A mitigating factor this summer, however, is the fact that west of the Rocky Mountains the summer has been either normal or cooler than normal in places like Seattle, Portland, San Francisco, and Los Angeles.

Christopher C. Burt
Weather Historian