37 US States Set Nighttime High Temperature Records This Summer

venice california summer night photo

photo: Sam Garza

With January to August 2010 found to be tied for the hottest year on record by NOAA, new analysis from NRDC shows that it wasn't just daytime temperatures that've been soaring. In fact, 37 states in the US set record high nighttime temperatures this summer. Dan Lashof, Climate Center director at NRDC noted,

Summer 2010 was the hottest on record in many locations in the United States. Not only was it hot during the day, but it didn't cool off at night. While one hot summer does not prove that global warming is happening, the long-term global trend does, according to the U.S. National Academy of Sciences, among others. The long, hot summer of 2010 follows the hottest decade on record and more record high temperatures can be expected in the future as heat-trapping pollution continues to build up in our atmosphere.

Half of US Weather Stations Saw Top-Five Record Nighttime Highs
Highlights of The Worst Summer Ever? report show that about 25% of weather stations in the contiguous United States the average low temperature at night for June through August 2010 was hotter than at at time since 1895 (in other words, for many of these, since records began being kept).

East of the Mississippi River, 40% of stations recorded a new record high nighttime temperature and 80% reported high temperatures among the five hottest ever recorded. Across the entire nation, more than half of weather stations fell into this latter category.

In total record high nighttime temperatures occurred in: Alabama, Arizona, Arkansas, Connecticut, Delaware, Florida, Georgia, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Virginia, West Virginia, and Wisconsin.

summer average temperatures US map

summer nighttime temperatures US map

maps: NRDC
Nighttime Temperature Trends Need More Attention
As for the impact of this, NRDC points out that hot, stagnant nights can be even more harmful for at-risk populations (elderly and low-income people who may not have access to air conditioning).

Furthermore, as recent studies have shown in regards to Asian rice crops, lack of cooling at night can have a more immediate effect on declining yields than the heating during the day. Data from the Philippines shows that for each 1°C decrease in daily minimum temperatures there's a corresponding 10% decline in crop yield. While that correlation can't necessarily be applied to yields in the United States, it's just an example of why it's not just high daytime temperatures that we need to pay attention to in determining possible future impacts of climate change.

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More on Global Climate Change:
2010 is Now Tied For Hottest Year on Record (So Far)
Arctic Now at Warmest Temperature in 2000 Years
2010 So Far Has Been Hottest Year on Record: NOAA
Canada Has Warmest (7.2°F Above Normal) and Driest (22% Below Normal) Winter on Record
Global Ocean Temperatures Warmest Since Records Began in 1880 (129 Years Ago!)

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