A look at weather extremes and the big-picture climate connections.

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.

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.

National:

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 Marchthird-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.

State-by-State:

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...

Local Records:

Temperature Location Old Record Date Set
118°F NORTON DAM, KS 113°F (3 days prior) June 28
115°F MCCOOK, NE 114°F (July 20, 1932) June 26
112°F GARDEN CITY EXP STN, KS 109°F (1 day prior) June 28
109°F ATHENS, GA 108°F (7/12/1930) June 29
107°F CHATTANOOGA AP, TN 106°F (1 day prior) June 30
106°F HUNTSVILLE INTL AP, AL 105°F (Aug 16, 2007) June 29
106°F ATLANTA HARTSFIELD AP, GA 105°F (Jul 17, 1980) June 30
106°F ST LOUIS SCI CTR, MO 105°F (Jul 30, 1999) June 30

St. Louis

The heat and drought have been especially intense in the Plains and the Midwest. Through July 20, St. Louis has had 24 straight days at 90°F or higher, which is that city’s second-longest such streak on record. The recordholder is 1936, when it had a streak of 28 straight days. St. Louis set its all-time June monthly high temperature record on June 28, with a temperature of 108°F. That was the hottest temperature observed since July of 1954. The all-time high temperature record in St. Louis stands at 115°F, set in . . . you guessed it, 1954.

On three straight days during June the temperature soared to at or above 105°F in St. Louis, tying or exceeding the previous all-time June high temperature record three times. Prior to this year, St. Louis had never had multiple days of 105-degree or higher temperatures in the month of June. 

St. Louis had its second-longest streak of triple-digit heat on record during the period from June 28 to July 7.

State-by-state breakdown of all-time record temperatures set during June 2012. Click on image for a larger version. Credit: NOAA/NWS.

Chicago

The summer is on pace to break the record for the most 90-degree days in a year, with 32 such days so far. The number to beat is 47 days, set in 1988. According to the NWS, “Chicago didn't see its 32nd 90-degree high temperature until July 31st, meaning 2012 is running nearly two weeks ahead of 1988!”

Washington, D.C.

It has been an extremely hot and stormy summer so far in the nation’s capital, with seven 100-plus degree days, tying 1988 for No. 2 on the all-time list. The record-holder is the summer of 1930, which had 11 such days. Washington also recorded its hottest June day in history when the temperature hit 104°F on June 29.

With a high of 102°F on July 8, Washington tied its record for the longest streak of 100-degree days, matching a record set during July of 1930. Washington also set a record with 11 straight days of 95-degree heat from June 28 to July 8.

Raleigh, N.C.

Raleigh tied its all-time record high with a temperature of 105°F on July 8, and broke its record for the longest streak of consecutive 100-degree days. The temperature reached or exceeded the triple digits on six straight days from July 3-8.

Ft. Wayne, Ind.

According to the NWS, “High temperatures reached or exceeded 90°F on at least 22 consecutive days (June 27 - July 18) in Ft. Wayne, shattering the mark originally set from July 11-24, 1983.”

Colorado Springs, Colo.

Colorado Springs, which was damaged by the deadly Waldo Canyon Wildfire during June, had its warmest June on record with an average temperature of 73.2°F, which handily beat the old record of 70.8°F. Colorado Springs set an all-time high temperature record of 101°F on June 26, breaking the record of 100°F. According to the NWS, Colorado Springs recorded three straight days of triple-digit heat. Previously, Colorado Springs had only hit the century mark on four other occasions since records began in 1894.

Links to More Record Temperature Information

Climate Central's June-July Heat Wave Coverage

National Weather Service Mid-July Briefing on Heat and Drought (pdf)

National Climatic Data Center's Temperature Extremes Page

June State of the Climate Report: Supplemental Data

« Extreme Planet