Frigid temperatures have returned to the Bay Area, prompting the National Weather Service to issue frost advisories and freeze warnings for much of the region.

Overnight temperatures are expected to plunge into the low 30s with daytime highs peaking in the low 50s for wide swaths of the Bay Area for the next few days.

Overnight frost advisories starting at midnight Monday and running until Wednesday morning have been issued for non-coastal areas in the North Bay and Central Coast, all interior valleys, as well as mountains and hill regions throughout the area.

Also, freeze warnings were issued for interior North Bay and East Bay areas, as well as Santa Clara hills and interior Monterey and San Benito areas.

The cold will bring dangerous conditions for unsheltered people, as well as pets, plants and exterior pipes.

The skies will be mostly sunny but two storm systems are expected to hit the region later this week.

The first rainstorm is forecast to arrive Thursday after 4 p.m. and continue through Friday, followed by a brief lull before the second storm arrives late Saturday.

There will be fewer impacts from the wet weather than a previous series of storms that came through the region in late December and earlier this month, according to Alexis Clouser, a National Weather Service meteorologist.

"Soils are still quite wet but have had a two-week drying period," Clouser said. "We're not concerned with any flooding or anything like that. The totals for these next storms are quite low compared to what we saw in early January."

Most areas have less than an inch of rain forecast for the first storm, but some mountain areas could see as high as 1.5 inches. Clouser said details for the storm arriving Saturday are still developing.