Dangerous heat will persist across northern California Monday, but we finally have some relief ahead in your forecast this week. High pressure just to our east remains the dominant feature in our forecast today, and will keep us very hot and dry. The Excessive Heat Warning is set to remain in effect in the valley, foothills, and the west slopes of the Sierra through 9pm Monday night. The Excessive Heat Warning will expire at 8pm Monday night in Trinity County, 8pm Tuesday night in western Siskiyou County, and 9pm Tuesday night along the eastern slopes of the Sierra. We also have a Heat Advisory in effect through 8pm Tuesday in portions of eastern Siskiyou and Modoc Counties. The hot and dry conditions will keep fire danger elevated across our region Monday, and gusty winds in Modoc County have prompted another Red Flag Warning for high fire danger there from 2pm through 9pm Monday. We have clear skies over northern California for the start of your Monday, and we'll be sunny to mostly 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 50's to 60's overnight. Most of us will have wind out of the south to 10mph, and gusts up to 20mph this afternoon. Southwest winds to 15mph, and gusts up to around 30mph will be possible in areas of Modoc and Lassen Counties this afternoon and evening. Humidity will dip into the 8 to 22 percent range on Monday afternoon. High temperatures will end up in the 102 to 110 degree range in the valley, in the 92 to 100 degree range in the foothills, and in the 92 to 105 degree range in our higher elevations this afternoon.
The high pressure off to our east will start to shift further east over the next few days, and the return of onshore flow and the Delta Breeze will help to cool our temperatures by a few degrees each day through Thursday. This is the result of low pressure approaching the West Coast. Temperatures will end up in the upper 90's to triple digits in the valley through Wednesday, while mountain and foothill areas mostly top out in the 90's. The Northern Mountains will likely still have some cities in the triple digits through Wednesday afternoon. The onshore flow and Delta Breeze will continue to ramp up towards the end of this week, and that will cool us down into the below average to average range from Thursday through Saturday. Valley areas will end up in the 92 to 99 degree range from Thursday through Saturday, while mountain and foothill areas top out in the 80's to 90's. High pressure will then start to rebuild across our region late this weekend through early next week. That will result in temperatures climbing back into the triple digits in the valley Sunday into next Monday. Our extended forecast remains very dry. This isn't great news for fire danger, but the silver lining is that we are not expecting any thunderstorm activity. We also do not have any widespread wind events looking likely through your extended forecast.