More than 55 million people are currently under a Southern California heat alert across the San Joaquin Valley and parts of the northwest, including 20 of the West Coast’s most populous cities.
“Temperatures could exceed 110F in parts of the Southwest, where an excessive heat warning is currently in effect,” the Weather Prediction Center wrote.
The most dire areas will be in the southwest, where the heat will be most intense.
“Some records may be broken, but record high temperatures are very high at this time of year,” the NWS office in Los Angeles said. “Record broken or not, this prolonged heat wave is going to be very dangerous.
More than 100 records could fall in the West.
Prolonged heat wave for the South-West
The kind of heat that will be felt from San Diego to Los Angeles to Phoenix will be hard to bear even for the locals.
“This heat could be record breaking and will lead to a very high risk of heat illness,” the NWS office in Los Angeles said. “Triple digit heat is expected for many locations in the valleys and mountains. Even hotter conditions are expected over Labor Day weekend through early next week.”
The heat will start on Tuesday, with a gradual warming each day of the week, and it will peak by the end of the week.
The reason for the extreme conditions is an area of tenacious high pressure over the region, creating what meteorologists call a “heat dome”.
This intense heat dome causes the high pressure to act as a lid on the atmosphere. When hot air tries to escape, the lid forces it back down, warming it even more as it sinks.
The result will be intense summer heat, 10 to 15 degrees above normal.
“Excessive heat warnings are in effect for nearly the entire forecast area beginning Wednesday and will continue through next Monday,” the NWS office in Los Angeles noted.
Forecasts indicate temperatures of 110 to 115 degrees in the deserts and the San Fernando Valley, with temperatures of 90 to 100 along the coast. It’s hot enough to potentially break records there as well.
In Phoenix, the “dry heat” will give way to wetter conditions by Thursday and Friday.
This will cause the actual temperature to drop slightly, but Phoenix’s NWS warns that the humidity could actually make it hotter.
In Southern California, a few early clouds Friday morning could roll in, offering a brief respite from the heat — but that will be short-lived.
“There will be renewed warming leading to an oven-like day on Sunday,” the NWS office in Los Angeles said.
Even downtown Los Angeles could reach 100 degrees on Sunday, with Death Valley potentially hitting 125.
This heat extends into the San Joaquin Valley, where record high temperatures are possible.
“Confidence is growing that these are the hottest temperatures so far this year,” said the NWS office in Hanford, Calif.
“Record temperatures are possible from Thursday with the best chance of records Sunday and Monday when the peak of the heat is expected.”
The Labor Day holiday will be one of the hottest days of the event, with the heat likely to last well into next week, making heat-related illnesses a huge concern amid the heat. overwhelming.
Record heat for the Pacific Northwest
The maximum heat for the interior parts of the Pacific Northwest will be felt for much of this week, as high temperatures soar, especially in Seattle, Portland and Boise.
“Daytime highs between 10 and 20 F above normal and overnight lows between 15 and 20 F above normal are likely,” the Weather Prediction Center said.
The heat is expected to peak Wednesday with highs in the 90s and potentially hit triple digits for parts of the Western Basin near Spokane, Wash. – even breaking records.
“Highs are expected to reach 10 to 15 degrees above average as multiple locations may test daily records for maximum temperatures,” the National Weather Service in Seattle said.
Near Boise, Idaho, temperatures could reach 20 degrees above normal, with record heat expected through Tuesday.
And in Seattle, high temperatures are expected to peak in the upper 80s to low 90s.
The extreme heat is expected to kick in by the end of the week, bringing temperatures into the 70s for Labor Day weekend.
A tropical Labor Day system could be on the horizon
The tropics are also warming up ahead of the holiday weekend.
The National Hurricane Center is actively monitoring two areas of the Atlantic for tropical development, as we will most likely have our next named tropical system before Labor Day.
An area of low pressure several hundred kilometers east of the Lesser Antilles has the greatest potential to become “Danielle”.
“Although environmental conditions are only marginally favorable, gradual development of this system is expected over the next few days and a tropical depression is likely to form later this week,” the NHC said.
There is an 80% chance that this area will become a tropical system within the next five days, according to the NHC.
Forecast models point this system westward, staying north of the Caribbean islands and curving northward, avoiding the Bahamas.
The storm is expected to remain at sea for now, but things could change by next week.
Although the storm is expected to remain at sea, there will still be implications for the East Coast over Labor Day weekend.
The storm could create windy conditions and even strong rip currents for the East Coast. The storm’s proximity to the United States will determine the strength of the winds and rip currents. Closer to shore they will be stronger, further from shore they will be weaker.
The NHC no longer tracks the area in the Western Caribbean for development. However, this area still produces clouds and rain that will pump tropical moisture onto the Texas coast. This will increase the chance of rain in South Texas over Labor Day weekend.
Another area to watch is a tropical wave just off the coast of Africa. This area could also become a tropical depression in the next few days although its lifespan could be short.
“By the end of this week, the disturbance is expected to move over cooler waters and no further development is expected,” the NHC said.
CNN meteorologist Judson Jones contributed to this article.