Millions of people across the United States are facing a prolonged spell of dangerous heat this week, as a sprawling heat dome that led to record-breaking temperatures in the West over the weekend spreads east.
Marc Chenard, a meteorologist at the Weather Prediction Center, said parts of the Upper Midwest were expected to experience surging temperatures on Monday, with highs of 95 to 105 degrees Fahrenheit or more possible, especially across parts of North and South Dakota.
“Then on Tuesday, it moves into the Northeast, from the Great Lakes into New York State, and even toward Boston,” he said of the heat dome. “On Wednesday, it begins to shift south into parts of the Mid-Atlantic, and by Thursday and Friday, it’ll move into the Southeast.”
Across the northern Plains and northern Rockies, more than 11 million people from Utah, Wyoming and Montana to North and South Dakota, Minnesota, Wisconsin and Michigan remained under extreme heat warnings through at least the middle of the week.
Farther east, heat advisories stretched from Pennsylvania to Maine, including New York City and Boston. Temperatures in these areas are expected to climb into the 90s on Tuesday and Wednesday, while heat index values — which measures how hot it feels when humidity is combined with air temperature — could reach the low 100s.
Some daily record highs are possible, Mr. Chenard said, especially around Syracuse, N.Y., and Manchester, N.H.
The heat is being driven by a strong area of high pressure, also known as a heat dome, that developed over the middle of the country at the end of last week. Mr. Chenard said this weather pattern has trapped hot air over much of the Western and Central United States, allowing temperatures to build day after day.
It has already produced exceptional temperatures in parts of the West. On Sunday, Salt Lake City reached 109 degrees, while temperatures in Billings, Mont., climbed to 111 degrees, setting temperature records in both cities.
Mr. Chenard said much of the West had reached its peak heat over the weekend, although temperatures above 100 degrees are expected to linger through at least the middle of the week in some areas, particularly in parts of Colorado and Wyoming, before easing somewhat, into the mid-to-high 90s by the weekend.
Relief should arrive more quickly in the Northeast and the Great Lakes, where a slow-moving weather system is expected to push the hottest air away by the middle of the week, allowing temperatures to become closer to normal for this time of year.
At the same time, however, the heat will shift into the Southeast by Friday. Areas from the Carolinas to Florida, including Kentucky, Tennessee, Mississippi, Alabama and Georgia, are expecting temperatures to rise into the low-to-mid 90s through the weekend.