After below-normal temperatures midweek, weak offshore winds and clear skies will bring a warming trend starting Friday and highs on Sunday as much as 30 degrees above normal, according to the National Weather Service.
Coastal locations and downtown San Francisco could see highs in the 80s on Sunday. Weather officials said they can't rule out temperatures in the upper 80s to near 90 on Sunday afternoon in some spots along the coast.
In inland areas, temperatures in the 90s are expected in many areas on Sunday, with 100s expected in the warmest spots.
Record highs for this time of year are possible Sunday in places such as San Francisco, San Francisco International Airport and San Jose.
The record for that date at the airport is 91 degrees, which is also the record at Moffett Field near Mountain View.
Gilroy will probably be the hottest spot in the region and could reach 105 degrees, meteorologist Steve Anderson said.
Anderson said the heat will really only last one day. Saturday will be about 10 degrees cooler than Sunday and Monday about 5 degrees cooler.
Widespread cooling is expected by the middle of next week.