High pressure centered to our east continued to build west towards northern California on Saturday, and brought hotter temperatures to our region on Saturday afternoon. The ridge will continue to build west through Monday, and is expected to pull monsoonal moisture north into our region both Sunday and Monday. This will bring the potential for thunderstorms to northern California both days, with the most likely timeframe for active weather from Sunday evening through Monday night. This will increase our fire danger as the threat of lightning sparked fires will be added into our forecast. A Red Flag Warning for high fire danger is in effect for Modoc County through 8pm Saturday evending due to locally gusty southwest winds and very dry conditions. Siskiyou and Modoc Counties will be under a Red Flag Warning for high fire danger from 2pm through 8pm Sunday due to hot and dry conditions, with the threat of thunderstorms. A Red Flag Warning has been issued for portions of Lassen and Plumas Counties from midnight Sunday through 8pm Monday due to the threat of thunderstorms with gusty winds over very dry fuels. We also have a Fire Weather Watch that's been issued for the valley, foothills, and west slopes of the Sierra from 2pm Sunday through 5pm Monday. This is mainly due to the threat of isolated thunderstorm activity that could spark fires in those areas. We had plenty of sunshine across most of northern California on Saturday, but areas closest to the Dixie Fire and Beckwourth Complex still have very hazy conditions due to the smoke. Temperatures topped out in the upper 90's to lower triple digits in the valley on Saturday afternoon, while foothill and mountain areas ended up in the 80's to 90's. We've had south or southwest winds across our region this afternoon, but winds will shift to become out of the northeast overnight.
Temperatures will end up slightly hotter on Sunday, and we'll have the threat of thunderstorms returning to most of our region Sunday afternoon through Monday. The best chance for active weather still looks to stay along the east slopes of the Sierra into Nevada, but models are hinting at the potential for some instability in the valley, foothills, and west slopes of the Sierra Sunday evening through Monday evening. This will increase our fire danger both days as the threat of dry lightning returns. We'll have south or southwest winds again both Sunday and Monday afternoons. The high pressure off to our east is expected to shift enough to the east to take the potential for active weather out of our forecast on Tuesday. Temperatures will range from the upper 90's to lower triple digits in the valley through the extended forecast, while mountain and foothill areas mostly top out in the 80's to 90's. There will be potential for more active weather late in the week and next weekend, but model confidence is currently fairly low on that activity returning. We will continue to track the latest conditions and what that means for you and our fire danger across northern California, and make sure you're prepared for any active weather that could return.