A high-pressure system hovering over Southern California is expected to sizzle the region over the next week or so, forecasters said Tuesday as state officials issued a rare Flex Alert urging residents to economize. energy.

Temperatures in the Inland Empire and elsewhere in the region are expected to climb up to 10 degrees above normal, Los Angeles National Weather Service meteorologist Joe Sirard said. “Normal” temperatures for each day, he said, are calculated from daily averages collected locally over the past 30 years.

The upcoming heat spike comes during a Southern California summer that has already seen a series of heat waves.

The looming heat prompted California’s Independent System Operator, or ISO, on Tuesday afternoon to issue a Flex Alert calling on Southern Californians to reduce their energy use from 4 p.m. to 9 p.m. Wednesday. The ISO, which oversees the state’s power grid, aims to ensure grid reliability, as power consumption is expected to increase in abnormally high temperatures.

Sirard attributed the anomalous highs to an atmospheric phenomenon called an upper level ridge, which concentrates warm air over a particular location. This high pressure system has been responsible for the consistent highs this summer.

“It’s a consistently hot pattern, especially in inland regions throughout the week,” Sirard said. “There is a persistent area of ​​high pressure aloft over the area. What this does is keep the weather warm in the area and away from the beaches.

Sirard said areas with shallow marine layers like Woodland Hills and Van Nuys can expect the warmest temperatures. NWS forecast daytime highs of up to 102 degrees on Wednesday and into the upper 90s to end the week. The San Gabriel Valley can also expect upper 90s averages on Thursday and Friday.

Downtown Los Angeles and Long Beach can expect averages in the upper 80s through Friday. Coastal communities can expect some reprieve with averages this week in the upper 60s to lower 70s.

Temperatures are expected to drop this weekend due to stronger overland flow off the ocean, but the sizzling still isn’t expected to stop then.

“It’s the hottest time of the year. We’re probably cooling closer to normal this weekend, but even in the valleys it’s still upper 80s and lower 90s,” said Sirard. “Then it looks like the pattern could get a little warmer again next week, so probably another bout of five to 10 degrees above normal temperatures at some point next week.”

NWS San Diego meteorologist Stephanie Sullivan said temperatures across the Inland Empire will reach 90 degrees all the way to 104 degrees; San Bernardino and Hemet can expect highs of around 101, Lake Elsinore around 102. Interior Orange County will hit averages in the 80s this week.

Given the persistent heat, this time of year in Southern California is prone to wildfires. However, Sullivan noted that a recent wave of thunder and thunderstorms could put the San Bernardino and San Jacinto Mountains, where most of the fire rescue activity is concentrated, at particular risk. .

These thunder and lightning storms, which Sullivan says typically occur over mountain ranges every afternoon, are the result of a monsoon pattern that began in July and is expected to persist through september.

Sullivan urged caution when driving, hiking, camping or spending time near these storm hotspots.

“Whenever thunderstorms are forecast, it’s best to go early in the day and try to get out of the area around midday or so because that’s when it tends to kick in.” , Sullivan added.

Along with being aware of possible thunderstorms, Southern Californians should also avoid strenuous physical activity in the heat, stay hydrated, and remember not to leave pets or children unattended in cars.

The hottest times of the day are early to mid-afternoon, so outdoor activities should be planned accordingly, she added.

“You absolutely have to be aware of the weather,” Sullivan said.

Expected temperatures for Wednesday:

— Downtown Los Angeles: 88

—Fullerton: 91

— Long Beach: 83

—Anaheim: 92

—Mission Viejo: 91

— Pomona: 96

— Red Lands: 100

— Riverside: 101

— St. Bernardine: 101

— Lake Elsinore: 102

-Torrance: 81

—Van Nuys: 97

— Whittier: 93

Source: National Weather Service