ORLANDO, Fla. – This week on Forecasting Change, we look at what our warming planet means to our overnight lows.
Average summer nights in 2021 and 2022 rank as the two warmest on record for the contiguous U.S.
Our media partners at Climate Central tell us that during 2022, 66% of the contiguous U.S. (by area) experienced extremely warm summer nighttime temperatures. That’s more than double the area exposed to extremely warm summer days (28%). Here, extremely warm summer nights and days are those in the upper 10th percentile of the local summer temperature distribution over the period of record.
Also in 2022, 102 counties across the contiguous U.S. set records for hottest summer nights, while 19 counties set record summer daytime temperatures.
And since the start of summer 2023 (June 1), the U.S. has already set nearly twice as many records for extremely hot nights over extremely hot days.
Our warming climate makes heat extremes more frequent and intense in general — but this is happening especially at night. Here in Orlando, the trend is self evident since 1970.
Gainesville has shown even more warmth in the overnight lows.
Warming increases evaporation from the land surface and a warmer atmosphere can hold more of that evaporated moisture, leading to higher humidity and more cloud cover.
The resulting clouds can reduce daytime warming by reflecting some incoming heat from the sun back into space.
But after the sun goes down, clouds can amplify nighttime warming by absorbing heat from the land surface and re-emitting that heat back down toward the ground.
Parts of the globe that have experienced faster nighttime warming have also experienced increased cloud cover, specific humidity, and precipitation, likely due to the intensification of the water cycle in our warming climate.
You can listen to every episode of Florida’s Fourth Estate in the media player below: