Dangerous heat hits the West and South: Latest forecast

Thirty-five million Americans are on alert for dangerously high temperatures, with the center of the heat dome over the West.

On Monday, temperatures could reach a scorching 111 degrees in Phoenix, 108 in Las Vegas, 112 degrees in Palm Springs and 118 in Death Valley, California.

On the July 4 holiday, the record heat expands north. Portland, Oregon, could near its record high of 97 degrees.

Triple-digit heat is also baking the South.

The heat index -- what the temperature feels like with humidity -- is expected to climb Monday to 104 degrees in Dallas, New Orleans and Raleigh, North Carolina; 105 degrees in Jackson, Mississippi, and Naples, Florida; and 102 degrees in Tallahassee and Orlando, Florida.

Click here for tips on how to stay safe in the heat.

Meanwhile, severe weather is heading to the East Coast and the Plains on Monday.

Severe storms, including damaging winds and hail, are expected from New Jersey to South Carolina.

Heavy rain and possible flash flooding is in the forecast from New York City to New England.

Farther West, Montana, the Dakotas and Minnesota could also get severe storms.

On July 4, the severe weather will center over the Plains, especially from Kansas to Nebraska, where damaging winds may pose a threat as the fireworks begin.

ABC News' Kenton Gewecke contributed to this report.