By TAMMY WEBBER
Associated Press

CHICAGO (AP) – For millions of people enduring extreme heat and humidity this week, it feels like they’re living in a pressure cooker. And in a sense, they are.

Meteorologists say much of the United States is trapped under a heat “dome” caused by a huge area of high pressure that’s compressing hot, moist air beneath it.

The dome is producing temperatures in the mid-90s to low 100s, and heat-index levels well above 100 degrees from the northern Plains to Texas and from Nebraska to the Ohio Valley.

Meteorologists say the dome also pushes the jet stream and its drier, cooler air farther north. And hot, humid air from the Gulf of Mexico circulates around the dome and travels farther inland than normal.