Most of the Bay Area under heat advisory

Most of the Bay Area was under a heat advisory Tuesday as temperatures did not cool off as much as expected overnight, according to the National Weather Service.

Around 11 a.m., NWS Bay Area said a heat advisory would be in effect until 9 p.m. for all of the Bay Area except the immediate Pacific Coast zones and San Francisco.

Temperatures were expected to be in the mid-90s to low-100s.

"Mid/upper level cloud cover across the region … combined with temperatures forecast to reach the 90s (potentially exceeding 100 deg F in the warmest interior spots) across the interior made for widespread Moderate HeatRisk," the NWS said.

Tuesday is expected to be the hottest day of the week, and people should be wary of hot conditions causing heat illness outdoors.

While parts of the Bay Area felt humid, a San Ramon Valley Fire official said it can create a false sense of security when it comes to fire danger.

"The humidity that you feel can create a false sense of security to the fire danger, and it's the heat that can pull moisture from the plants, which increases fire danger," Deputy Chief Joe Bradley said.

Wildfire smoke expected to impact air quality

An air quality advisory was issued Tuesday due to smoke from the Little Fire, which has burned 950 acres near Pleasanton.

Bay Area Air District officials are expecting smoke from the fire to affect the air quality in the East Bay.

"Pollution levels are not expected to exceed the national 24-hour health standard. A Spare the Air Alert is not in effect," the air district said.