Summer Precipitation Trends
For most of the nation, summer weather has been changing over the past four decades or so — in ways climate scientists say are consistent with what they’d expect in a warming world.
The most obvious change is in summer temperatures where most of the continental U.S. has been heating up. With precipitation, the picture is more mixed: most of the West has gotten drier since 1970, while the Northeast, Southeast and northern Great Plains have gotten wetter. This is also consistent with what climate scientists expect in a warming world. Higher temperatures drive moisture out of the ground and into the atmosphere, and a warmer atmosphere can hold more water vapor. That means there is more moisture to drop when it does rain or snow. Also, very heavy precipitation events are clearly on the rise in the contiguous states, even in drier regions.
The one-line summary: The wet are getting wetter, the dry are getting drier, and everyone’s getting warmer.