US weather forecast: Dangerous heat wave, severe thunderstorms and flash flood threat to hit multiple states

Published 27 July 2026 · us

A dangerous combination of extreme heat, severe thunderstorms, flash flooding and monsoon-driven rainfall is expected to affect much of the United States through July 29

A dangerous combination of extreme heat, severe thunderstorms, flash flooding and monsoon-driven rainfall is expected to affect much of the United States through July 29, according to the Weather Service's (NWS) Weather Prediction Center (WPC). While a powerful heat dome continues to bake the central and southern US, multiple storm systems are forecast to bring damaging winds, hail and flooding from the Upper Midwest to the Northeast. Meanwhile, the annual North American monsoon is triggering heavy downpours across the Southwest. Here's what is happening and which places are most at risk. Why is the US facing such extreme weather? The Weather Prediction Center says a broad upper-level high-pressure ridge, often called a "heat dome," is parked over the central and southern United States. High-pressure systems suppress cloud formation and trap hot air near the surface. The result is prolonged sunshine, soaring daytime temperatures and unusually warm nights that prevent people and infrastructure from cooling down. At the same time, disturbances moving along the northern edge of the ridge are colliding with warm, humid air from the Gulf of Mexico, creating ideal conditions for severe thunderstorms. Meanwhile, the Southwest remains under the influence of the North American monsoon, bringing moisture from the tropics that fuels heavy rainfall and thunderstorms.

Which states are under the dangerous heat wave? The most dangerous heat is expected across Texas Oklahoma Kansas Nebraska Arkansas Louisiana Mississippi Alabama Georgia Parts of Tennessee Portions of the Southern Rockies The Desert Southwest, including Arizona, Nevada and southeastern California Daytime temperatures are forecast to reach Upper 90s to low 100s°F (37°C-40°C) across much of the Plains and Southeast. Between 115°F and 120°F (46°C-49°C) in isolated parts of the Desert Southwest. Humidity will make conditions even more dangerous, with heat index values expected to exceed 105°F to 115°F (40°C-46°C). Overnight temperatures are also expected to remain unusually warm, staying in the 70s°F in many locations, increasing the risk of heat-related illness. The Weather Prediction Center has issued Major to Extreme HeatRisk for large portions of the Southern Plains, Mississippi Valley and Southeast. Where are severe thunderstorms expected? A cold front stretching from the Upper Midwest into the Ohio Valley will interact with warm, humid air to produce widespread thunderstorms. On Monday, the greatest severe weather risk covers parts of Minnesota Wisconsin Michigan Illinois Indiana Ohio The Storm Prediction Center has placed these areas under an Enhanced Risk (Level 3 of 5) for severe thunderstorms. Forecasters warn the storms could produce Damaging wind gusts Large hail Frequent lightning Heavy rainfall Why is flash flooding a concern?