SAN FRANCISCO (BCN) — A freeze warning was issued for much of the Bay Area for this weekend, National Weather Service officials said Friday morning.

The coldest temperatures are forecast for Saturday night and Sunday morning, with many areas dropping into the lower and mid-30s.

Some parts of the North Bay and southern areas of the Santa Clara Valley may even drop into the 20s, NWS officials said.

There is a frost advisory for the San Francisco Bay shoreline and a freeze warning for the North Bay tonight and Saturday night.

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A freeze warning for Saturday night into Sunday was issued for the East Bay interior valleys and hills, Santa Clara Valley south of San Jose, and the interior of Monterey County, including the Salinas Valley.

Freezing temperatures can jeopardize the safety of vulnerable populations, outdoor animals and unprotected plants, NWS officials said.