Hercules
California, USA
Long-term weather forecast
Long-term weather forecast

December weather forecast and climate
Hercules, CA

Ocean temperature

In December, the average ocean temperature in Hercules, California, is 54.1°F (12.3°C).
Note: Swimming in 54.1°F (12.3°C) is considered life-threatening. Even a few minutes in 55.4°F (13°C) water is uncomfortable, and swimming below 50°F (10°C) may cause total loss of breathing control and cold shock, depending on a person's physique.

Daylight

The month with the shortest days in Hercules is December, with an average of 9.6h of daylight.

How cold is the water in December in Hercules?

In December, the average ocean temperature in Hercules is 54.1°F (12.3°C). At temperatures below 50°F (10°C), swimming in a suitably protected swimsuit is feasible; otherwise, cold shock and loss of breathing control are imminent. Even a short swim, without thermal protection, at temperatures around 55.4°F (13°C) is not comfortable.

What is the month with the shortest days in Hercules?

December has the shortest days of the year in Hercules, California, with an average of 9.6h of daylight.

How many hours of daylight does Hercules have in December?

The average length of the day in December in Hercules, California, is 9.6h.
Average sea temperature in December - Hercules, CA
  • Average sea temperature in December: 54.2°F

The best month for swimming (with the highest average sea temperature) is September (57°F).
The coldest month (with the lowest average sea temperature) is April (52.6°F).

Average daylight in December - Hercules, CA
  • Average daylight in December: 9.6h

The month with the longest days is June (Average daylight: 14.8h).
The month with shortest days is December (Average daylight: 9.6h).