The NWS San Francisco CA issued a frost advisory at 1:44 p.m. on Wednesday valid from 11 p.m. until Thursday 9 a.m. The advisory is for North Bay Interior Valleys, East Bay Interior Valleys and Southern Salinas Valley/Arroyo Seco and Lake San Antonio as well as Monterey County.

Temperatures in parts of the San Francisco Bay Area were expected to drop into the upper 20s to the middle 30s for the second morning in a row Tuesday, triggering a Freeze Warning and Frost Advisory.

The eventual U.S. departure further threatens the central goal of the agreement to avoid a rise in global temperatures of 1.5 degrees Celsius, a target that appears even more tenuous as last year was the planet's hottest on record.