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July 22, 2025

Anna Murray 

This summer has brought exceptionally high humidity to many parts of the United States, with numerous regions experiencing record-breaking levels of atmospheric moisture.

In the eastern U.S., May marked the return of the uncomfortable humidity that often characterizes summer. Earlier that month, the National Oceanic and Atmospheric Administration (NOAA) had already forecasted a potentially wetter summer for most major cities along the East Coast.Rising temperatures and increased humidity are largely driven by climate change. But what exactly is causing the heightened humidity this year? The primary factor is the unusually warm waters in the Atlantic Ocean and Gulf of Mexico.

These warm waters have led to record levels of "precipitable water"—a meteorological term for the total amount of moisture in the atmosphere. So far in 2025, National Weather Service offices have issued more flood warnings than in any other year since records began in 1986. The devastating flash flood in central Texas on July 4th was the deadliest in at least 50 years in the United States.