Near-record warm weather is expected to arrive in the Central California and the Mother Lode this week.
The change in conditions is the result of high pressure building over the Central Coast.
The National Weather Service expects the biggest change along the coast, inland areas and the Central Valley.
An "Excessive Heat Watch" advisory was issued Monday for most of the Bay Area, where highs in the 90s were forecast through mid-week.
In the Sierra foothills, daytime high temps will gradually increase through midweek, peaking Thursday.
The high in Sonora is forecast to climb from 86 degrees today to 92 degrees by Thursday - well above average but short of the record. The record high temperature for May 15 was 95 degrees, set in 1972.
The overnight lows will range from 46 tonight to 50 degrees Thursday night.
In Angels Camp, which will host the Calaveras County Fair and Jumping Frog Jubilee this week, a high temperature of 93 is slated for Thursday, opening day.
Cooling is expected through the weekend, with a high Friday of 89, Saturday 81 and Sunday 76 in Angels Camp.
Regional hot spot Copperopolis is expected to heat up to 94 on Thursday before cooling back down into the low 80s and high 70s for the weekend.
The National Weather Service urges people to be prepared for the heat. That includes wearing appropriate clothing and drinking plenty of water.