The warmest day of a Southern California heat wave will bring temperatures well into triple digits Friday before a hot weekend.
Temperatures over 100 degrees are expected throughout the valleys, meaning an excessive heat warning for the valleys and mountains through Saturday evening. Temperatures will drop only slightly Saturday before a more significant cooldown Sunday.
"We're running well above the average," said NBC4 forecaster Crystal Egger. "We've also added in a slight northerly wind. It's dry, and it's blazing hot again today."
The heat, dry conditions and wind bring increased fire danger risk. A red flag warning is in effect until midnight Saturday in the Los Angeles County Mountains, Angeles National Forest and Antelope and Santa Clarita valleys.
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Friday's highs will hit the mid-80s at the beaches and the upper 90s to triple digits inland, with temps hovering around 105 to 110 degrees in parts of the San Fernando, Santa Clarita, San Gabriel and Antelope valleys.
The persistent heat is due to a "dome of hot air" over the region, Egger said.
"It's like putting a lid on top of hot water on a stove. It just continues to heat up."
This map says it all. Stay safe as it heats up: Drink water, stay out of the sun, and check on your neighbors. pic.twitter.com/c1qFTmq2IV— President Obama (@POTUS) July 20, 2016
The three-day stretch marks the 10-year anniversary of one of the hottest series of days on record for any month in Southern California. On July 22, 2006, the temperatures in Woodland Hills reached 119, the all-time high for any of our climate stations.
Inland areas could see higher-than-normal temperatures as late as next Tuesday, although coastal areas should see some cooling beginning Sunday. The Coachella Valley is entering the third day of a heat wave, and highs are expected to range from 114 to 119 degrees in the valley.
Temperatures inland will not quite reach the record-breaking marks seen late last month, but desert residents can expect the mercury to hover around 115 degrees until at least Tuesday.
Friday's high in Riverside is expected to be 109. A high of 117 degrees was recorded in Palm Springs on Thursday, along with marks of 116 degrees in Thermal and 114 degrees in Indio.
The "heat dome" is covering much of the United States, leaving hundreds of millions of Americans in sweltering conditions. Twenty-one states are under a heat alert with some areas climbing above 115 degrees with high humidity.
Even President Obama tweeted a reminder about the dangerous conditions.