SAN FRANCISCO (KGO) -- An Excessive Heat Warning is in effect for almost all of the Bay Area except for Solano County, beginning at 11 a.m. and lasting into Wednesday with the possibility of getting extended. The advisory was upgraded from a Heat Advisory around noon on Monday.
A Spare the Air alert is in effect Monday for moderate to poor air quality.
WATCH: Heat stroke vs. heat exhaustion - how to tell the difference
The hottest days will be Tuesday and Wednesday with widespread 90s/100s
It has been two years since San Francisco has been in the 90s, and there's a good chance that happens Tuesday.
VIDEO: Extreme heat dangers and safety tips: What you need to know
There are currently only light offshore winds in the forecast (5 - 15mph), no Red Flag Warnings but still elevated fire danger with the heat
It will be slightly cooler by Friday, but no dramatic cool down as the upcoming weekend is still warm.
RELATED STORIES & VIDEOS: