The heat dome that smashed all-time records in the northern Rockies and Northern Plains is now spreading searing heat and humidity across the Midwest and East. Numerous daily record highs could fall from the Midwest to the Northeast during the next few days.
(MORE: What is a heat dome?)
Heat alerts
The map below shows where the National Weather Service has issued heat alerts, including extreme heat warnings and heat advisories, stretching from the Northern Plains to New England and the mid-Atlantic states.
Weather in your inbox
Extreme heat warnings are issued when heat-related illnesses, including heat exhaustion and heat stroke, become more certain.
This is the time to plan to suspend all major outdoor activities if a warning is issued. If you do not have air conditioning, locate the nearest cooling shelter or discuss staying with nearby family or friends who have air conditioning.
(MORE: 5 things to know to stay safe in a heat wave)
Midwest, Northeast heat forecast
The hot, humid air will very slowly wane in the Midwest and East through the remainder of the week, but it will remain warm.
Many of these areas will see temperatures soar into the 90s by the afternoon. A few areas in the Midwest and East Coast could approach 100 degrees on Wednesday.
This will set some daily record highs Wednesday in parts of the Northeast from New England and upstate New York to the mid-Atlantic states.
On Wednesday, Baltimore, Philadelphia and Atlantic City could all hit 100 degrees, which would set a daily record in all three cities. New York City could top 100 degrees, which could also set a record.
Morning lows, especially in larger cities, may languish in the middle or upper 70s, offering little evening or nighttime relief.
(MORE: America’s deadliest weather is heat, not tornadoes or hurricanes)
When will relief arrive?
A fairly strong cold front is forecast to plunge out of eastern Canada into the northern tier of states on Wednesday. A secondary cold front will follow right behind the first later this week.
That will bring some heat relief from the northern Great Lakes to northern New England by Wednesday, then to more of the Midwest and Northeast starting Friday into the weekend from north to south.
(MAPS: 10-day US forecast highs and lows)
West heat forecast
In general, any changes in the heat in the Rockies and Northern Plains this week will be subtle.
We won’t see the all-time record heat of last Sunday repeated, but highs in the 90s will be common much of this week in lower elevations of the Northern Plains and Rockies.
Historic heat records were tied or broken
This heat wave already rewrote the history books in parts of four states on Sunday.
Montana’s largest city, Billings, topped out at 111 degrees, easily topping its previous all-time record of 108 degrees.
Miles City, Montana, soared to 115 degrees, obliterating its previous record of 111 degrees and just 2 degrees shy of the state’s all-time record and the high in Death Valley’s Stovepipe Wells Sunday.
Salt Lake City also had its hottest high in over 150 years Sunday, topping out at 109 degrees.
Elsewhere, Sheridan, Wyoming (109), and Idaho Falls, Idaho (103) broke their all-time records, as well.
(CURRENT MAPS: Temps | Heat Index)