North Bay frost advisory in effect through Friday morning

The first frost of the Fall season in northeast Ohio coats maple leaves in a yard in Moreland Hills, Ohio on Sunday, Oct. 19, 2008. (AP Photo/Amy Sancetta)

The National Weather Service in San Francisco has issued another frost advisory in effect from 3 a.m. to 8 a.m. Friday.

Temperatures are expected to drop into the middle 30s by Friday morning with the coldest reading expected around sunrise.

This advisory affects North Bay valleys including; Santa Rosa, South Santa Rosa, Napa, San Rafael, Petaluma, Novato and Rohnert Park.

Frost can harm or kill unprotected plants and vulnerable populations like the homeless, who struggle to keep warm. It is advised to bring outdoor animals indoors who may be struggling to keep warm.

Sensitive plants may be killed if left uncovered.

KTVU Meteorologist Mark Tamayo says frost advisories in the Bay Area are normal this time of year. This is the second frost advisory this season and happens to be the second in a row from Wednesday night's.