Southern California braces for another heat wave this week

After a brief reprieve of cool temperatures over the weekend, Southern California is expected to get hit with another heat wave this week that could bring periods of elevated fire risk, according to forecasters.

Temperatures are likely to stay around the 90-degree mark in the Los Angeles area for most of the week, said John Dumas, a meteorologist with the National Weather Service. Inland and valley areas are expected to see triple-digit temperatures.

A high-pressure ridge is forecast to build over the area, bringing northerly offshore winds that heat up and dry out the air as they travel downhill and squeeze through mountain passes, Dumas said. The winds will cut off the afternoon sea breeze that usually mitigates the heat from earlier in the day, particularly in coastal areas, he said.

“This effectively shuts off our natural air conditioning system,” Dumas said.

Gusty winds were expected to begin developing below passes and canyons in the Santa Ynez Range of southern Santa Barbara County on Sunday night. North to northeast winds will also affect the Interstate 5 corridor and valleys of eastern Ventura County as well as northern and western L.A. County.

A heat advisory for much of the region is expected to go into effect at 11 a.m. Tuesday and continue until 5 p.m. Friday, according to the weather service.

The National Weather Service is projecting that the combination of elevated temperatures, low humidities and moderate winds will result in elevated to briefly critical fire conditions.

“It hasn’t rained since March or so,” Dumas said. “So it is still very dry out there.”

California just recorded its hottest September on record, according to the National Oceanic and Atmospheric Administration, and the state looks to be stuck in a nearly endless loop of hot, dry weather.

With a strong La Niña developing, the dry pattern is looking ever harder to break, and could be settling in to stay for a while, forecasters said.

Arizona and California experienced their warmest April-to-September period in 126 years, the Drought Monitor reported. New Mexico and Nevada had their second-warmest such period.

With the monsoon season essentially a no-show this year, Utah and Arizona recorded their driest period ever during that same six-month stretch. New Mexico had its second-driest and Colorado had its third-driest. Arizona’s newly established statewide precipitation record came in more than 2 inches drier that the previous record.

California is already experiencing its worst fire season on record, surpassing 4 million acres burned — more than double the state’s previous record.