Intense rainstorms are becoming more frequent in most of the U.S. — though experts say where they occur and whether they cause catastrophic flooding is largely a matter of chance.

Sweltering heat more commonly seen in the throes of summer than in the spring is making an unwelcome visit to a large portion of the U.S. – from the Dakotas to Texas and other parts of the South – prompting forecasters to tell residents to use caution outside.

Scorching temperatures meteorologists say were brought on by a heat dome have taxed the Texas power grid and threaten to bring record highs to the state before they are expected to expand to other parts of the U.S. National Weather Service Forecaster Bob Oravec said Monday that the heat dome is expected to reach north to Kansas City and east to the Florida Panhandle and continue at least until the July Fourth holiday.