Low pressure overhead and to our South has continue to provide some showers and the chance for thunderstorms across Northern California today, but temperatures have ended up much warmer than Sunday. Showers are mostly in the mountains as we head into your evening and that is also where we'll have the best chance for thunderstorm activity tonight. Valley areas had some showers very early in the day but have become mostly sunny this afternoon. Temperatures ended up in the low to mid 80's in the valey, in the mid 70's in the foothills, and in the 60's to 70's in the moutnains this afternoon. Winds have mostly been out of the Southwest and light today.
A ridge of high pressure building into our region from the Desert Southwest will result in dry weather and much hotter temperatures on the way through the middle of this week and the National Weather Service out of Sacramento has issued a Heat Advisory for the valley and foothills from 11am Tuesday through 8pm Thursday. Skies will be sunny to mostly sunny on Tuesday and temperatures are expected to end up 10 to 15 degrees warmer than Monday. Valley areas will start out in the low to mid 60's and will end up in the mid to high 90's on Tuesday afternoon. Foothill areas will dip into the low to mid 60's overnight and will end up in the 80's to low 90's on Tuesday. Mountain areas can expect low temperatures in the 40's and high temperatures in the mid to high 80's on Tuesday. Winds will be out of the North to around 10mph.
The high pressure down to our Southeast will continue to be the main driving factor in your forecast through Thursday of this week. Temepratures are expected to peak in the high 90's to triple digits in the valley on Wednesday and will be a degree or two cooler on Thursday. Overnight low temperatures are only expected to dip into the 60's to low 70's, so there will not be much in the way of relief from the heat overnight. Foothill areas are projected to have high temperatures in the 90's on Wednesday and Thursday, while mountain areas end up in the 80's to 90's. Low temperatures in the foothills will only dip into the 60's to low 70's overnight, and mountain areas will be dipping into the 50's. There is a slight chance for some showers and thunderstorm activity in the Sierra on Wednesday evening, but current projections are keeping that to our South.
Low pressure off the coast of Southern California will start to track Northeast through our region on Friday and another area of low pressure will be approaching the West Coast from the Gulf of Alaska during that same time. That will result in a slight chance for showers returning to portions of Northern California as early as Friday night, and a good chance for showers returning to portions of our region on Saturday. The best chance for showers currently looks to be in higher elevations and the far Northern portion of the valley. This will also result in a decent cooling trend on the way in your forecast. Valley high temperatures are projected to dip back into the high 80's to low 90's on Friday afternoon, while foothill and mountan areas dip back into the 70's to low 80's. We'll then have temperatures in the 70's to 80's in the valley on Saturday, while foothill and mountain areas top out in the 60's to low 70's. We could see some showers lingering on Sunday and Monday, with the best potential for wet weather in higher elevations. Valley areas will be sunny to mostly sunny again on Monday, but temperatures are still projected to end up in teh 70's to low 80's. Mountain and foothill areas will continue to top out in the 60's to low 70's on Monday of next week.