Nearly half the U.S. population is forecast to face the 2025 heat season’s most dangerous heat — record‑breaking in some areas — extraordinary even by the sweltering standards of the “dog days of summer.”
Over the next several days, tens of millions of people will experience dangerous heat stress levels, with high temperatures and humidity and low wind speed. Wet Bulb Globe Temperature (WBGT) is an index specifically designed to measure these combined factors, providing a clearer understanding of heat risk. Learn more about WBGT.
Day‑by‑day, the number of people forecast to be at the highest heat threat based on WBGT:
🔴 Saturday, July 26: ~49 million people in the U.S.
🔴 Sunday, July 27: ~76 million people in the U.S.
🔴 Monday–Wednesday, July 28–30 (Peak): ~130–150 million people (or ~40–45% of the US population)
You can track real-time heat stress forecasts with Klimo WBGT on the web, or by downloading the app from the Apple App Store or Google Play Store.
Heat remains the deadliest weather-related hazard in the U.S. Hydrate, rest often, and help others stay safe.
