Get ready for another hot and active day across northern California on Monday. The Excessive Heat Warning remains in place for the valley and foothills through 9PM on Wednesday night, and the Red Flag Warning for high fire danger has been extended through 9pm tonight for valley and foothill areas. The Red Flag Warning is in effect from 10AM through 8PM today in Trinity County, and from 8AM through 11PM in areas of Siskiyou and Modoc Counties.
Skies are cloudy this morning and thunderstorm activity has persisted in portions of Plumas and Lassen Counties overnight. More thunderstorm activity looks likely in the valley through the day, with the best potential along and west of I-5. Higher elevations will see an uptick in the potential for thunderstorms this afternoon and evening. Thunderstorms are also expected to be likely in most mountain areas through the day. The clouds have helped to trap in the heat and temperatures are starting out warm again this morning. Valley and foothill areas are ranging from the 70's to low 80's this morning, and mountain areas are starting out in the 50's to 60's early today. Winds are starting out of the northeast to around 10mph, and will pick up to around 10mph out of the northwest this afternoon, with gusts up to around 20mph. The potential for lightning sparked fires will be a big concern again today, and gusty winds in the afternoon could result in rapid fire spreads. High temperatures are projected to end up in the 100 to 105 degree range in the valley this afternoon, in the mid to high 90's in the foothills, in the low to mid 90's in the Sierra, and in the 90's to low triple digits in the Northern Mountains. The threat of thunderstorms is expected to continue into tonight, but the latest models are showing the active weather wrapping up around midnight.
We'll be staying somewhat cloudy on Tuesday and getting several degrees hotter than Monday. There will stil be a threat of thunderstorms, but that mostly looks to be over the Sierra on Tuesday. High temperatures will range from the 104 to 112 degree range in the valley on Tuesday, while foothill and mountain areas top out in the mid 90's to triple digits. Temperatures are not expected to be as hot on Wednesday, but will still be well above average for this time of year. Skies will be sunny to mostly sunny, and temperatures will finally fall into a range closer to average for this time of year on Thursday. Valley areas will still end up in the 90's to around 100 degrees, while most mountain and foothill areas end up in the 80's to mid 90's. The heat will then kick back in for the end of this week and weekend, but is not expected to be as extreme as Tuesday or Wednesday. Valley areas will end up in the high 90's to around 105 degrees this weekend. Mountain areas will mostly top out in the 90's through the weekend. Latest models are also hinting at impacts from another tropical storm to our south late this week through the weekend, which could bring more active weather to our extended forecast. Please make sure to plan ahead for the heat and the high fire danger through your extended forecast.