A rapid and intense heat event is spreading across the United States, starting in the Southwest and expanding east. What began as a regional spike is now affecting a large portion of the country, bringing unusually high temperatures far earlier than expected. Forecasters warn that up to 23 states could be impacted by a powerful “heat dome,” with temperatures rising as much as “30 degrees above what’s normal for late March.”

The heat first hit states like California, Nevada, and Arizona, and is now moving into central regions including Texas, Kansas, Missouri, Illinois, and the Dakotas. Areas that typically experience mild spring weather are now facing conditions more like peak summer, with a sudden and unusual jump in temperature.

A “heat dome” forms when high pressure traps hot air close to the ground. This system blocks clouds and prevents cooling, allowing heat to build throughout the day. As a result, temperatures in some areas, especially Texas and Nevada, could reach or exceed 100°F, breaking long-standing records.

Even cooler regions like the Midwest and Great Plains are being affected. Temperatures that usually range between 40–60°F in March may rise into the 80s, catching many people unprepared for the sudden change.

The National Weather Service has issued warnings, not only for the heat but also for increased wildfire risk. Dry conditions combined with high temperatures create a dangerous environment where fires can spread quickly. Already, dozens of cities have set new heat records, showing how severe and widespread this event has become.