Why is it so hot in March in Southern California?

This week’s Extreme Heat Warning across Southern California has shattered records — but why is it so hot in March? Well, there’s a reason it feels more like summer.

According to NBC Los Angeles meteorologist Belen De Leon, a high-pressure system paired with a few other factors are the culprits.

A ‘very tall’ high-pressure system

“During March, usually we see high-pressure systems, but they’re weaker and they don’t last very long,” De Leon explained. “But right now, we have a massive, record-strong, high-pressure system over the Southwest, and it’s not just affecting us here in Southern California.”

De Leon said the current high-pressure system is extending very high into the atmosphere, “more like something you’d see in the middle of the summer.”

“[The high-pressure system] is very tall. So, the taller and the stronger that high pressure system is, the more air it pushes down,” she said. “And, when air sinks, it warms and it compresses. When that air compresses, it heats up. Plus, we’ve got clear skies, wall-to-wall sunshine — that’s what causes the temperatures to climb so quickly during the day.”

De Leon said the biggest issue with this system is that it’s not budging.

“It’s not moving; there’s nothing to push it out of the way,” she explained. “That’s why we have this extended heat wave. The heat is building, records are falling, and even our nights are unusually warm.”

SoCal heat records, smashed

NBCLA meteorologist David Biggar said many Southern California heat records were broken on Wednesday — and more heat records, including all-time March records, are likely Thursday and Friday.

“Palm Springs may approach the record for the ‘Hottest March Day’ in the US,” he added.

Here are some of Wednesday’s record-breaking stats:

• 82 degrees at LAX: Broke the 79-degree record from 1988
• 87 degrees at UCLA: Broke the 84-degree record from 1978
• 87 degrees in Idyllwild: Broke the 75-degree record from 2004
• 91 degrees in Long Beach: Broke the 86-degree record from 1960
• 92 degrees in Palmdale: Broke the 84-degree record from 1997
• 93 degrees in Lancaster: Broke the 85-degree record from 2004
• 95 degrees in Anaheim: Broke the 88-degree record from 2010
• 95 degrees in Santa Ana: Broke the 88-degree  record from 1978
• 95 degrees in Downtown Los Angeles: Broke the 87-degree record from 1997
• 97 degrees in Burbank: Broke the 89-degree record from 1978
• 98 degrees in Riverside: Broke the 93-degree record from 1914
• 100 degrees in Woodland Hills: Broke the 92-degree record from 1997

Biggar said the record-temp in Idyllwild also broke that community’s record for the all-time hottest day in March.

As Southern Californians battle the excessive heat, the increase in temperatures is putting a pressure on power grids. Macy Jenkins reports for the NBC4 News at 11 p.m. on Wednesday, March 18, 2026.

Thursday and Friday: ‘The top of the roller coaster’

De Leon said Thursday’s temps will also reach record highs. Here are some temps from NBCLA’s First Alert Forecast:

• 97 degrees in Los Angeles
• 99 degrees in Van Nuys
• 100 degrees in West Covina
• 101 degrees in San Bernardino
• 102 degrees in Riverside
• 102 degrees in Lake Elsinore

The high temps will stick around through Friday; the Extreme Heat Warning expires at 8 p.m. Friday.

“Today and tomorrow, we’re at the top of the roller coaster,” De Leon said. “And then, some relief this weekend.”

The extended heat wave brings a higher risk for heat illness. Lauren Coronado reports for the NBC4 News at 6 a.m. on March 17, 2026. 

What’s next?

According to De Leon, the high-pressure system will shift somewhat east this weekend. That will bring slightly cooler temperatures to the region, but not by much.

“So that’s going to keep our temperatures running way above where they should be for this time of year,” she said. “Next week, it stays hot and it’s still going to feel like summer.”

The high-pressure system will linger through next week.

De Leon said next week’s temps will be in the upper-80s and low-90s — but at least there won’t be triple-digits.