A strong ridge of high pressure to our South has kept us sunny, hot, and dry across Northern California today. The Excessive Heat Warning is still in place for the valley and foothills, and will stay in effect through 7pm Thursday evening. Temperatures topped out in the 90's to triple digits in the valley, and in the 80's to 90's in the foothills and mountains. Winds have mostly been out of the South to 10mph this afternoon, but some more favorable spots like Chico had winds up to 15mph. Humidity dipped to below 30 percent across the entire valley and to below 40 percent in the foothills and mountains. The hot and dry conditions resulted in moderate fire danger for most areas this afternoon. The bigger concern is the risk of heat related illness.
Thursday will be almost identical to Wednesday across Northern California. One change is The National Weather Service out of Sacramento has added in a Heat Advisory for Trinity County and Western Shasta County from noon through 6pm on Thursday. Temperatures will start out in the 60's to low 70's in the valley and are projected to top out in the triple digits on Thursday afternoon. Foothill areas will start out in the 60's to mid 70's and will end up in the low to mid 90's on Thursday. Mountain areas will start out in the 50's, and are projected to end up in the low to mid 90's in the Sierra, while portions of the Northern Mountains end up in the mid to high 90's. Winds will be out of the South to 10mph, and humidity is expected to dip into the 15 to 25 percent range on Thursday afternoon.
We'll be staying hot on Friday, but clouds will be increasing in the afternoon. The current projection has high temperatures in the mid 90's to low triple digits in the valley on Friday, while mountain and foothill areas end up in the 80's to low 90's. The ridge of high pressure to our South will be moving off to the East by Friday evening, and an area of low pressure will be tracking North along the California coast. The low pressure moving into our region will bring an increase of clouds late in the day on Friday and the chance for showers and thunderstorms to our our forecast on Friday night. The best chance for thunderstorms will be late Friday night through Saturday afternoon. Mountain areas will have the best potential for active weather on Friday night and that chance for active weather becomes more widespread on Saturday. Heavy rain, a good chance for thunderstorm activity and much cooler temperatures are on the way for your Saturday. We'll have high temepratures plummeting into the 70's in the valley and into the 60's for the foothills and mountains. Gusty winds, periods of heavy rain, and hail will be possible in areas impacted by thunderstorms.
The area of low pressure that brings the active weather to our region on Saturday is expected to move North into the Pacific Northwest by late Saturday night/early Sunday morning. Northern California will be partly cloudy, and will have a very modest chance for some light showers on Sunday. We'll end up back in the low 80's in the valley on Sunday, and higher elevations will climb back into the 70's. Similar conditions are expected for the start of next week, but there will be a slightly better chance for some light showers. We'll be drying out and warming back up as we head towards the middle of next week. The current projection puts valley areas back into the high 80's to low 90's on Tuesday and Wednesday under partly cloudy skies.