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Over 50 million people will be under extreme heat alerts this holiday weekend

(CNN) More than a dozen states could see record temperatures this holiday weekend.

Every state along and west of the Continental Divide will have temperatures above average Saturday through Monday. The eastern half of the country will begin to see a shift to slightly cooler, more seasonal temperatures this Labor Day weekend.

Record heat for the West

Nearly 45 million people were under excessive heat watches or warnings on Thursday, and that number is expected to rise to over 50 million this weekend as the extreme heat spreads east into other states.

While the main heat wave really ramps up Friday for most areas of California, Sunday is expected to be the hottest day, with temperatures as high as 115 degrees expected away from beaches, according to the National Weather Service.

More than 125 record highs will be possible Saturday through Monday, with even more records possible for warmest low temperatures in the same time frame.

"Death Valley is forecasting highs of 125°F for for consecutive days this Friday through Monday," says , CNN meteorologist Pedram Javaheri. "That would not only shatter daily records for all four days, making it the hottest September run of heat on record, but also set a new September all-time high."

Javaheri said that out of the 3,240 September days on record since 1911, Death Valley has only recorded nine of those days at or above 120°F in September. Incredibly, the next five days are all forecast to exceed that number!

The National Weather Service even warned that this weekend is expected to be worse than the region's recent August heat wave, which prompted rolling blackouts in the area.

Another scary prospect is that all the extreme heat will lead to high fire danger over the weekend into Labor Day.

Temperature rollercoaster for Midwest

For Minnesota, Iowa, Nebraska and the Dakotas, Saturday will still feel like summer with temperatures well above average. By Monday, that all changes as those same states see a drop in high temperatures by 15-20 degrees.

Take Fargo, North Dakoka, for example, going from a high temperature of 80°F on Saturday to 65°F on Monday. Rapid City, South Dakota, will go from 94°F Saturday to 73°F on Monday. Other cities such as Chicago, St. Louis, Oklahoma City and Dallas should also take note of that temperature change, as that colder air will continue to spread south and east next week.

In addition to temperature changes, there is a stark difference in rain chances for the weekend. For Chicago, Milwaukee, Green Bay and Traverse City, Michigan, it will be full sunshine on Saturday, but a quick change to showers and thunderstorms for Sunday.

Retreating heat for Southeast

After a very warm week, this weekend will be quite refreshing for the Carolinas and Virginia. Several days this week have included heat advisories and/or excessive heat warnings for the region, as temperatures were in the mid-90s with heat index levels in the triple digits.

For Saturday, Sunday and Monday, those temperatures cool into the low to mid-80s for Raleigh, North Carolina, and Norfolk and Richmond, Virginia. Wilmington, North Carolina, and Myrtle Beach, South Carolina, will see temperatures drop into the low to mid-80s, but residents will have to contend with some pop-up showers and thunderstorms.

Other areas that have been plagued by heavy rain and flooding the past few days will finally get some drier air. Dallas, Oklahoma City, and Little Rock, Arkansas, will see sunshine all three days of the holiday weekend, after having been in flood watches earlier in the week.

For those along the Gulf Coast still cleaning up from Hurricane Laura, it will still be a steamy weekend. Temperatures for Beaumont, Texas, and Lake Charles, Louisiana, will be in the mid-90s, with heat index levels in the upper 90s to low triple digits Saturday through Monday. There will also be some low-end thunderstorm chances each day across the region, mainly on Saturday and Sunday.

Sneak peek at Autumn for Northeast

For the Northeast, this holiday weekend will provide the first look at autumn. With dry air in place for much of the region, and temperatures at or slightly below normal, it will be quite refreshing after a very hot summer.

In fact, record-breaking heat for some. New York City (LaGuardia), Burlington, Vermont, Portland, Maine, State College, Pennsylvania, and even Providence, Rhode Island, all topped out as their hottest summer (June 1-August 31) on record.

This weekend, though, New York and Baltimore are looking at full sunshine, with high temperatures in the low 80s Saturday through Monday.

Boston and Providence also have sunshine, but with highs in the mid- to upper 70s -- putting them all at just a few degrees above average temperatures for the start of autumn.

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