Fire weather forecast for Riverside, San Bernardino, San Diego counties this week, NWS warns

A wildfire burned 350 acres north of Moreno Valley earlier in October. Ryan Ponitz photo

The National Weather Service on Tuesday upgraded a fire weather watch that was set to go into effect this week to a full-blown red flag warning amid predictions of gusty winds and low humidity.

The original fire weather watch was set to begin late Wednesday night and remain in effect through Friday evening. The newly-imposed red flag warning will now go into effect at 5 a.m. Thursday and last until 5 p.m. Friday, the National Weather Service said.

A red flag warning means a combination of strong winds, low humidity and warm temperatures are expected to create conditions ripe for extreme fire behavior.

The San Bernardino, Riverside and San Diego county mountains, foothills and inland valleys will all be at increased risk of fire, the NWS said. In Riverside County, most of the western portion of the county along with the San Gorgonio Pass and northern parts of the Coachella Valley, are included in the watch area.

East to northeast winds of 25 to 35 mph, with gusts up to 50 mph, are forecast for the region, with humidity of 5% to 10%, according to the NWS.

Will Fritz can be reached by email at

2:20 p.m. Tuesday: This story was updated to indicate the fire weather watch imposed Monday has been upgraded to a red flag warning.