Let’s start with the good news: The Lower 48 has reached peak summer, backed by 30 years of seasonal temperature trend data from Bloomberg. 

Now for the bad news: A heat wave continues to set records across the Lower 48, with 150 million Americans under weather alert this holiday weekend. 

Axios outlines the areas where the heat dome will impact the most: 

Nearly half the U.S. population is under some type of extreme heat warning or advisory on Friday. The extreme heat in the Southeast to Mid-Atlantic is oppressive, with a strong upper-level high-pressure area, or heat dome, leading to hot and humid conditions.

Heat advisories and other alerts extend from New Orleans to New York City on Friday.

In the West, though, a near-record-strong heat dome is yielding scorchingly hot and dry conditions, and raising wildfire risks.

Excessive heat warnings along the West Coast stretch from Nevada and Arizona through California and northward into Oregon and Washington State.

National Weather Service meteorologist Jenn Varian told Bloomberg that Las Vegas is forecasted to hit a scorching 117F on Sunday into early next week, potentially tying the metro area’s all-time high recorded in 2005 and again in 2017.

“Confidence is increasing that this potentially historic heatwave will last several days,” the National Weather Service’s office in Portland, Oregon, wrote on X, adding temperatures will rise “into the 100s and 110s over much of California and southern Oregon.” 

Here are more forecasted highs this weekend (list courtesy of Axios):

118°F: Forecast high in Redding, Calif., on Saturday, tying the city’s all-time high.
128°F: Forecast high in Death Valley, Calif., just 2-degrees shy of the hottest reliably measured temperature on Earth.
100°F: Forecast high on Friday in Portland, Ore., with temperatures at or above this level from Friday through Tuesday in this typically cooler city.

This all means that power grids will be under stress this weekend as high temperatures boost air conditioning demand. Bloomberg says that grids in California and Texas should be closely monitored for an elevated blackout risks.