High pressure off to our east in the Desert Southwest and to our west in the Pacific will dominate our forecast today and through your Labor Day Weekend. This will result in a substantial rise in temperatures through this weekend, and more stagnant air across northern California. The lighter winds will allow more impacts to our air quality from wildfire smoke late this week and this weekend. We're already starting to see bigger impacts to air quality in areas surrounding active fires and that will likely become more widespread over the next few days. An Excessive Heat Watch has been issued by the National Weather Service out of Sacramento for the entire valley, foothills, a portion of the western slopes of the Sierra, and the Northern Mountains from Saturday morning through Tuesday afternoon.
Skies are mostly clear this morning, but smoke will continue to become more of an issue across our region today. Most of the valley is starting out with air quality in the moderate range this morning, while bigger impacts are being reported in Plumas and Lassen Counties. The worst air quality is in Plumas County, where air quality is starting out in the very unhealthy range this morning. Temperatures are starting out in the 60's to 70's in the valley and foothills this morning, and in the 50's to 60's in higher elevations. Winds are mostly light and out of the northeast this morning, but will increase to around 10mph out of the southeast this afternoon. Humidity will mostly end up in the 20 to 35 percent range later today. High temperatures are projected to end up several degrees warmer than yesterday. Valley areas will top out in the mid 90's to around 100 degrees, while foothill areas end up in the mid 80's to low 90's, Sierra locations end up in the high 80's to mid 90's, and the Northern Mountains top out in the mid 90's to low triple digits. Lighter winds and slightly higher humidity will help to limit fire danger today, but dry fuels are keeping us in the moderate to high range this afternoon.
Temperatures will end up a degree or two hotter on Friday and then the heat will ramp up as we head through your Labor Day Weekend. Valley areas can expect high temperatures in the 100 to 106 degree range on Saturday, and in the 103 to 112 degree range on Sunday. Foothill and mountain areas are currently projected to top out in the mid 90's to triple digits for both days this weekend. The latest projections have temperatures dropping by around 2 to 5 degrees on Labor Day compared to Sunday. This will still be around 10 degrees hotter than average for this time of year. Temperatures will drop by a couple more degrees on Tuesday and then by a couple more on Wednesday. High temperatures are expected to stay above average through your entire extended forecast. Heat related illness will be a major concern through this weekend and into early next week. The Excessive Heat Watch is set to be in effect from Saturday morning through 6PM Tuesday. Make sure to plan ahead for the hot conditions. Make plans to be inside somewhere with air conditioning for the afternoons on those days, drink plenty of water, and dress for the hotter temperatures on the way.