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Petaluma River entrance, San Pablo Bay Sea Temperature in December

California, United States

November Petaluma River entrance, San Pablo Bay year-round → January

Average sea temperature for Petaluma River entrance, San Pablo Bay, United States across December, based on 10 years of daily readings.

Average

12.15° C

High

13.81° C

Low

10.6° C

Water at this temperature is cold and will feel very cold initially, but the body will get used to it and longer swims are possible. Experienced swimmers can manage several hours of swimming, however hypothermia is still a real risk.

December is the 7th warmest of 12 months at Petaluma River entrance, San Pablo Bay. On average the water sits 0.9° than the year-round mean of 13.09° C.

Compared to November, December is 0.9° cooler than (13.07° C in November). By January the water is usually 12.01° C.

Petaluma River entrance, San Pablo Bay Day-by-Day Water Temperature in December

10-year low, average and high

10.0° C
11.1° C
12.3° C
13.4° C
14.5° C
1
5
10
15
20
25
31
Day-by-day low and high band with the 10-year daily average through December. Range Average

Each vertical bar above is one day of December. The shaded band covers the range the water has reached on that day across the last 10 years — the lowest reading at the bottom, the highest at the top. The line running through the bars is the daily average over those 10 years, so you can see the typical shape of the month at Petaluma River entrance, San Pablo Bay.

A narrow band means the temperature on that day has stayed close to the average year on year. A taller band means it has swung more, often because of changeable weather around that time of year. Hovering a day pulls up its low, average, and high.

December Water Temperature Table for Petaluma River entrance, San Pablo Bay

10-year daily averages

Day Average Low High
December 1 12.43° C 11.47° C 13.79° C
December 2 12.44° C 11.27° C 13.77° C
December 3 12.43° C 11.28° C 13.62° C
December 4 12.4° C 11.23° C 13.54° C
December 5 12.35° C 11.26° C 13.52° C
December 6 12.36° C 11.33° C 13.44° C
December 7 12.36° C 11.32° C 13.34° C
December 8 12.33° C 11.28° C 13.25° C
December 9 12.35° C 11.34° C 13.17° C
December 10 12.32° C 11.29° C 13.22° C
December 11 12.22° C 11.1° C 13.19° C
December 12 12.13° C 11.08° C 12.99° C
December 13 12.07° C 11.08° C 13.03° C
December 14 12° C 11.04° C 13.03° C
December 15 11.95° C 10.93° C 13.12° C
December 16 11.9° C 10.76° C 13.29° C
December 17 11.94° C 10.92° C 13.2° C
December 18 11.95° C 10.87° C 13.23° C
December 19 11.95° C 10.84° C 13.25° C
December 20 11.96° C 10.63° C 13.42° C
December 21 12° C 10.6° C 13.38° C
December 22 12.05° C 10.67° C 13.36° C
December 23 11.99° C 10.6° C 13.42° C
December 24 11.98° C 10.62° C 13.49° C
December 25 12.02° C 10.64° C 13.59° C
December 26 12.03° C 10.67° C 13.62° C
December 27 12.08° C 10.73° C 13.64° C
December 28 12.1° C 10.64° C 13.61° C
December 29 12.18° C 10.64° C 13.81° C
December 30 12.2° C 10.6° C 13.7° C
December 31 12.15° C 10.64° C 13.61° C

Where December Sits in the Year

December highlighted

8.0° C
10.6° C
13.3° C
15.9° C
18.5° C
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
12.01° C
12.05° C
11.89° C
11.95° C
11.89° C
13° C
14.13° C
15° C
15.38° C
14.59° C
13.07° C
12.15° C
10-year monthly history for Petaluma River entrance, San Pablo Bay. Bars span historical low to high; the line marks the monthly average. Range Average
January → February → March → April → May → June → July → August → September → October → November → December →

Nearby Locations in December

Compare other United States water for the same month

Petaluma River entrance, San Pablo Bay Location

38.1153, -122.5057

38.11530, -122.50570 View on OpenStreetMap →

Petaluma River entrance, San Pablo Bay sits at 38.1153°N, 122.5057°W, on the coast of California, United States. The marker on the map shows the spot the readings on this page come from. It usually sits a short distance from the town centre, out on the open water itself, so the numbers stay tied to the coast rather than a generic point inland.

Coastlines bend, headlands focus the water, and the temperature can run noticeably differently between two beaches that look close together on a map. Comparing nearby locations is a quick way to see how local geography is shaping the readings.

Nearest locations to Petaluma River entrance, San Pablo Bay