We've had above average temperatures across northern California this week, and we'll only get hotter as we head through this weekend. High pressure centered to our east is building west into northern California, and will drive our very hot and dry conditions through at least this weekend. This will be the dominant influence on our forecast. Our dry fuels, and very dry air will keep fire danger high for all of northern California today. A Red Flag Warning for high fire danger is set to be in effect from 2pm through 8pm Thursday for eastern Siskiyou County and most of Modoc County due to very dry air and fuels, hot temperatures, and locally gusty southwest winds. We are starting out with clear skies this morning and will stay sunny through the day. Temperatures are starting out in the 60's to 70's in the valley and foothills, while mountain areas have dipped into the 40's to 50's for the start of your Thursday morning. Most of us have light winds out of the northeast this morning, and will have south winds to around 10mph this afternoon. Stronger winds can be expected in areas closest to the Oregon and Nevada borders. Humidity will dip into the 7 to 24 percent range in the valley Thursday afternoon, but will likely be even lower in Modoc and Siskiyou Counties. Valley areas are projected to climb into the 102 to 108 degree range Thursday afternoon, while foothill and Sierra locations top out in the upper 80's to upper 90's, and the Northern Mountains end up in the mid 90's to lower triple digits later today.
Temperatures will only get hotter as high pressure continues to build west into northern California through this weekend. The Excessive Heat Watch has now been upgraded to an Excessive Heat Warning for the valley, foothills, Sierra, Trinity County and western Siskiyou Counties. This will start at noon on Friday and last through 9pm Monday for the valley, foothills, and portions of the Sierra. It will start at noon on Friday, and last through midnight Sunday in Trinity and western Siskiyou Counties. The eastern slopes of the Sierra will be under the Excessive Heat Warning from noon Saturday through 9pm Monday. We also have a Heat Advisory that's been issued for eastern Siskiyou County and Modoc County from 2pm Friday through 1pm Sunday. Valley temperatures will end up in the 105 to 113 degree range on Friday, while foothill and mountain areas climb into the 90's to triple digits on Friday afternoon.
The hottest temperatures ahead are expected on Saturday and Sunday. Valley areas will end up in the 110 to 116 degree range through this weekend, while we still climb into the 90's to triple digits in our mountain and foothill areas. This is dangerous heat on the way for our afternoons, and little relief from the heat in the overnight hours. Valley and foothill areas can expect low temperatures to end up in the 70's to 80's through this weekend, while mountain areas have low temperatures in the 50's to 60's. Make sure you're staying hydrated, dressing for the heat, and avoiding outdoor activities in the peak heat of the day between 10am and 7pm. Heat related illness will be very possible with these conditions through this weekend. Low pressure will track through to our north early to mid week next week, and will bring a downward trend in our high temperatures, but we'll still have above average temperatures continuing through your entire extended forecast. There is no rain in sight, but the good news is we do not have any big wind events expected in our forecast either.