It's Cold in These Parts, With More Chill to Come

Update, Thursday 11:30 a.m.: If you think of weather records as history, then this was a historic morning in the Bay Area. The National Weather Service in Monterey is reporting record temperatures across what we'll call the Greater Bay Area — its forecast area includes the nine counties touching the bay plus Monterey, San Benito and Santa Cruz counties.

Among the records: San Rafael, 30 degrees, breaking the record of 31 set in 1972; downtown Oakland, 34 (previous record: 34, set in 1972); Oakland airport, 30 (previous record: 35, set in 2006); Mountain View, 32 (previous record 33, set in 1998); Salinas airport, 27 (previous record: 29, set in 1942). San Jose hit 29 degrees and downtown San Francisco was at 40, both tying records set in 1972.

The most eye-popping readings this morning? Healdsburg, at 16 degrees, and Napa Airport, at 19 degrees. It's not clear whether those are official records. Further afield, a place called Moody Canyon, in San Benito County east of Pinnacles National Park, had a low of 9 degrees. In the Sierra, it was 0 at Truckee, just across Donner Pass, and 8 at South Lake Tahoe.

Forecasters say we'll see more of the same tomorrow, with freeze warnings remaining in place for Friday morning. The very cold, clear weather will give way to cold, rainy or snowy weather, depending on where you are, Friday night and Saturday. Snow levels could be as low as 1,000 feet around San Francisco Bay, and forecasters say snow could fall over much the Sacramento and San Joaquin valleys. A winter storm watch for the Sierra Nevada says as much as two feet of snow could fall over the highest elevations; a foot is possible in the Sierra foothills.

Original post (Wednesday, Dec. 4): That frost you might have seen this morning doesn't lie — it's cold this morning. The National Weather Service says the chill broke records only in Salinas, where a 28 degree reading broke the mark of 29, set in 2004. But though temperature records stayed intact throughout the rest of the Bay Area, it was still the coldest morning of the season so far throughout the region.

The coldest temperatures were recorded in the region's interior valleys, with lows in the mid- to upper 20s in many locations in outlying Sonoma, Marin, Alameda, Contra Costa, and Santa Clara counties. Most locations near the bay and coast stayed in the mid-30s to low 40s. High temperatures are expected to stay in the mid-40s to mid-50s, about 10 degrees below normal for most locations.

The weather service has issued a freeze warning for the entire Bay Area outside San Francisco through Friday morning. Forecasters have also put out a hard freeze warning for the Central Valley, warning citrus farmers and others of temperatures that will plunge into the low 20s, and stay there, for the next several nights. California Citrus Mutual, an industry group, says Wednesday morning temperatures were not low enough to cause significant damage to crops in the valley.

Here's a National Weather Service table of record low temperatures throughout the region for this time of year: