Sunrise from Otay Mountain
Sunrise on Monday from Otay Mountain. Image from UCSD HPWREN camera network

Santa Ana winds will sweep through parts of San Diego County Monday as temperatures heat up amid low humidity, significantly raising the risk of wildfires throughout the region, according to the National Weather Service.

A wide area of high pressure will build over the western United States Monday, ushering in hot and dry weather in Southern California through Thursday, forecasters said.

The weather service issued a red flag warning from 5 a.m. to 5 p.m. Monday for the San Diego County mountains and the western valleys.

Sustained winds Monday out of the east and northeast are expected to be between 15-20 mph, with gusts possible reaching 30 mph, forecasters said. Daytime humidity is expected to drop to 10-15 percent throughout the region.

The red flag warning means that outdoor burning is not recommended, and any fires that develop will likely spread rapidly, according to the NWS. Wind speeds are expected to weaken Monday evening, but low humidity and dry fuels will elevate the risk of wildfires through at least Thursday.

The weather service also issued a heat advisory that will be in effect from 10 a.m. Tuesday through 8 p.m. Thursday in the western valleys.

High temperatures Monday are forecast to reach 78 degrees near the coast, 86 inland, 90 in the western valleys, 97 near the foothills, 91 in the mountains and 106 in the deserts.

The mercury could reach the triple digits in many western valley communities on Tuesday and Wednesday, forecaster said. Highs in the deserts are expected to drop to 105 on Tuesday, then rise to 109 on Wednesday.

— City News Service

Chris Jennewein is Editor & Publisher of Times of San Diego.