Record Summer Temperatures, By The Numbers

The weather this summer has been so extreme that it has rivaled the most destructive and unbearable summers in U.S. history, years that are infamous in weather lore. Those years include 1934 and 1936, which were in the middle of the Dust Bowl era, as well as 1954 and 1988, which was the year that Yellowstone National Park burned and NASA scientist James Hansen first warned the U.S. Senate about the consequences of manmade global warming.

Each dot on this map represents a temperature record set during June of 2012. Click on the image for a larger version. Credit: Climate Central.

Each dot on this map represents a temperature record set during June of 2012. Click on the image for a larger version. Credit: Climate Central.

As a reporter and analyst on the extreme weather and climate change beat, I’ve found this summer to be dizzying, with too many extreme events and broken records to count, let alone write about. First it was the heat, then the wildfires, and now the ever-expanding drought that seems intent on swallowing the entire country and kicking off a global food crisis. Oh, and there has been more extreme heat. On Friday, in fact, several states in the High Plains were under heat watches and warnings, but they’re used to that by now. After all, this is the summer of sweat. It’s also a summer that offers a vivid and disturbing preview of what’s to come as a result of manmade global warming.

I’ve compiled some of the most impressive temperature records that I gathered from the National Weather Service’s labyrinthine network of websites, and will be updating this weekly as the summer continues. I plan to add noteworthy precipitation records to the Extreme Planet blog as well.


The U.S. recorded its warmest January-to-June period on record and its warmest 12-month period.

The warm June followed the warmest spring on record, which was the culmination of the warmest March, third-warmest April, and second-warmest May. This marks the first time that all three months during the spring season ranked among the 10 warmest, since records began in 1895.

In June, said NOAA scientists, the average daily temperature for the lower 48 states was a full 2.0°F above the 20th-century average.

The U.S. Climate Extremes Index, which tracks the highest and lowest 10 percent of extremes in temperature, precipitation, drought and tropical storms/hurricanes, was a record-large 44 percent during the January-to-June period. That was more than twice the average value, driven largely by warm daily high and warm overnight low temperatures.

During June, there were at least 3,282 daily record high temperatures broken or tied, and at least 1,955 records for warmest overnight low temperature. Of these records, 645 were monthly records, and 173 were all-time temperature records.

Sidney Municipal Airport in Nebraska did its part to add to the daily record total by breaking or tying an impressive 20 daily temperature records during June, out of a possible 63 such records during the month.

Through July 18, there have been 3,369 record daily highs broken or tied, and 2,456 record warm overnight low temperature records set or tied. Of these, 349 have been monthly records, and 197 have been all-time records.

In a long-term trend that demonstrates the effects of a warming climate, daily record-high temperatures have recently been outpacing daily record lows by an average of 2-to-1, and this imbalance is expected to grow as the climate continues to warm. According to a 2009 study, if the climate were not warming, this ratio would be expected to be even. However, you’ll notice that shorter time periods will have much more lopsided ratios, including this year when daily record highs are outnumbering daily record lows 9-to-1. Or, when you look at all warm temperature records, including overnight low temperatures compared to all cold temperature records, the ratio is closer to 7-to-1.


On a state-by-state basis, Colorado set the highest number of daily high temperature records during June, with 343, followed by Texas (337) and Kansas (230). Tennessee set the most all-time records in June, with 27, followed by Colorado (23) and Kansas (21). In Colorado, June 2012 was the warmest June on record, with temperatures averaging 6.4°F above average. Seven other Western states had a top 10 warm June.

A scientific panel known as the U.S. State Climate Extremes Committee is reviewing a temperature reading of 113°F in South Carolina, and 112°F in Georgia, to determine if they qualify as the warmest temperature ever recorded in those states.

Curious about some of the noteworthy records set in U.S. cities? Here’s a brief city-by-city rundown. (You can also explore these records and more using Climate Central’s Record Temperature Tracker.) More to come I’m sure…



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