New Delhi, March 24 -- After smashing March heat records in 14 states and the U.S. as a whole, the gigantic heat dome that's baked the Southwest is creeping eastward and may end up being one of the most expansive heat waves in American history, meteorologists and weather historians said.

And it's not going away for awhile, maybe not till the middle of the next week as April starts, said meteorologist Gregg Gallina of the National Weather Service's Weather Prediction Center.

"Basically the entire U.S. is going to be hot," Gallina said Monday. "The area of record temperatures is extremely large. That's the thing that's really bizarre."

This heat dome - in which high pressure is acting like a pot lid trapping hot air over a region - will ...