Much of the Bay Area and Monterey Bay region will face excessive heat this weekend due to a high-pressure system from the southwest, according to the National Weather Service.
Daytime highs throughout much of the Bay Area are expected to be between five and 15 degrees above normal, rising into the high 90s and 100s on Friday and Saturday in the region's interior areas and into the 80s and 90s along the coast.
Meteorologists with the weather service are forecasting the heat wave to wane slightly on Sunday, only for the region to warm back up early next week to levels even higher than Friday and Saturday.
Overnight lows are expected to sit in the upper 50s and low 60s in the Bay Area's valleys and in the 60s and 70s for the hills and mountains.
Preceding the heat wave could be a thunderstorm by way of Tropical Storm Elida, which is currently making its way up the Baja California coast, according to the weather service. Isolated thunderstorms could pop up on Thursday and Friday but are not as likely as the heat wave.
"Overall, we're moving into our warmest time of year, late August into early September," the weather service said.
Region under Spare the Air alert on Aug. 14
The Bay Area Air Quality Management District has issued a Spare the Air alert for Friday because of excessive smog expected in the region.
The alert, the third issued by the air district for smog this year, is the result of a forecast of light winds and temperatures of up to triple digits in inland parts of the Bay Area that will combine with vehicle exhaust to create an unhealthy level of smog, otherwise known as ozone.
Smog can cause breathing problems and other medical maladies, so the air district encourages Bay Area residents to only exercise outdoors in the early morning hours when smog concentrations are lower, as well as to work remotely and avoid long car trips to limit the levels of vehicle exhaust.
People can find out when a Spare the Air alert is in effect by visiting sparetheair.org, calling 800-HELP-AIR (4357-247), downloading the Spare the Air smartphone app for iPhone or Android devices or connecting with Spare the Air on Facebook, Twitter or YouTube.