A Santa Ana wind event packing gusts up to 75 mph will ratchet up wildfire danger beginning Saturday evening throughout the Inland Empire, the National Weather Service said.
The agency on Friday revised its prior High Wind Watch to a High Wind Warning, beginning at 11 p.m. Saturday and concluding at 10 p.m. Monday, though breezy conditions were expected to continue beyond that time.
“This is currently favored to be a moderate Santa Ana event, with peak gusts generally 45 to 65 mph, with isolated gusts to 75 mph,” the NWS said in a statement. “As is typical with Santa Ana winds, drier air will be coming into the region, dropping relative humidity values each afternoon below 15% away from the coast, falling as low as 5% in portions of the Inland Empire.”
The agency said the extremely low humidity and stiff winds “will lead to periods of critical fire weather conditions Sunday and Monday, with near-critical conditions continuing Tuesday and Wednesday, as weaker offshore winds prevail.”
The Riverside County Emergency Management Department issued a statement saying the “increased fire hazard (could result in) public safety power shutoffs” in locations where risks are greatest.
The agency recommended that residents keep track of potential shutoff zones by checking rivcoready.org/active-events.
According to forecasters, a surface ridge of high pressure will anchor over the Great Basin in Nevada and Utah, moving in behind a low pressure system as it exits eastward, generating the Santa Ana winds.
The agency predicted northeast winds averaging between 20 and 30 mph will be the norm, with higher speeds in mountains and passes, including the San Gorgonio Pass between Beaumont and Whitewater.
“Strong winds could damage trees and other objects,” the agency said. “Travel could be difficult, especially for high-profile vehicles.”
The winds will be lighter Tuesday and will dissipate Wednesday as a trough displaces the high pressure system over the Great Basin.
High temperatures in the Riverside metropolitan area will peak in the mid 70s over the weekend, with overnight lows in the low 50s. The mercury will climb into the low 80s early next week.
In the Coachella Valley, daytime temperatures will settle in the low 80s through the weekend, with lows in the mid 50s. There will be little change going into next week.
In the Temecula Valley, weekend highs will be in the low 70s, with lows dropping to around 50. The same warm-up in the Riverside area will be felt in the southwestern section of Riverside County, forecasters said.