Daytime highs will be mostly in the low 70s to low 80s on the coast, in the high 70s to high 80s around the bay, and in the low to high 90s inland. Overnight lows will be mostly in the mid 60s with some interior areas reaching the high 60s.
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Forecasters say the Bay Area is warming up Tuesday after more than a week of cooler-than-normal weather, with even hotter conditions expected Wednesday and Thursday.
The NWS says the marine layer is now limited to a few hundred feet near sea level, with only a few patches of fog along the Big Sur coast.
A Heat Advisory is in effect across the region now through 10 p.m. Thursday. Moderate to major HeatRisk is expected, especially for people without effective cooling or enough water.
Minor coastal flooding is also likely for about an hour around Tuesday's high tide in low-lying bayshore areas of Marin County. High tide at the San Francisco gauge is expected to be about 1 foot above normal at 9:59 p.m. Tuesday, according to forecasters.
Spare the Air Alert in effect
The Bay Area Air District has issued a Spare the Air alert for Wednesday because of a forecast of unhealthy air quality due to high temperatures and light winds in the region.
The air district said the weather conditions are expected to contribute to elevated levels of ozone, otherwise known as smog, particularly in the East Bay and South Bay.
Ozone can cause health problems, particularly in children, older people and those with respiratory or heart conditions, according to the air district, which advises people to only exercise outdoors in the early morning hours on Spare the Air days.
The National Weather Service has issued a Heat Advisory for Wednesday and Thursday in the Bay Area because of temperatures that could reach 105 degrees in some inland locations. The advisory will be in effect from 10 a.m. Wednesday through 10 p.m. Thursday.