We had hot temperatures and mountain thunderstorms across northern California on Saturday afternoon. Our weather is being driven by high pressure off to our east, and low pressure to our south through this weekend. The threat of thunderstorms will persist through the night in the northern Sierra and southern Cascades. Thunderstorm activity has prompted a Flood Advisories in Lassen County from 5pm through 8:30pm Saturday evening, where 1 to 2 inches of rain were observed in a short period of time. A Red Flag Warning for high fire danger has also been issued for portions of Modoc, Lassen, and Plumas Counties from 11pm Saturday through 11am Sunday due to the threat of thunderstorms accompanied by dry lighting and locally gusty winds. Thunderstorm activity is expected to stay along or east of the Sierra crest through tomorrow morning, and will then return to areas east of the Sierra crest on Sunday afternoon. Our high temperatures topped out in the 90's to triple digits in the valley, 80's to 90's in the Sierra and foothills, and in the 90's to lower triple digits in the Northern Mountains this afternoon. We are expecting to have similar temperatures ahead for your 4th of July forecast, but most areas will have a dip of one or two degrees compared to today. Temperatures will start out in the 60's to low 70's in the valley on Sunday and end up in the 90's to lower triple digits. Foothill areas will start out in the 60's, while mountain areas dip into the 50's to 60's overnight. High temperatures will top out in the 80's to 90's in our foothill and mountain areas on Sunday afternoon.
High pressure will stay off to our east, but will continue to be the main driving factor in our forecast for next week. We will have sunny skies, and well above average temperatures through our extended forecast. Valley areas will top out in the upper 90's to triple digits all week, while foothill and mountain areas mostly end up in the 80's to 90's. Overnight low temperatures will also stay very warm. Valley and foothill areas will have low temperatures ranging from the 60's to 70's, and mountain areas will dip into the upper 40's to lower 60's all week. High pressure to our east is expected to build west late in the week, and bring even hotter temperatures to our region. Valley areas will end up back in the 108 to 115 degree range next weekend, while mountain and foothill areas will climb back into the 90's to triple digits. If the current forecast holds we will have another Excessive Heat Warning as we get closer to next weekend.