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

September weather forecast and climate
Mendocino, CA

Ocean temperature

In Mendocino, California, in September, the average water temperature is 54.9°F (12.7°C).
Note: 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.


The average length of the day in September is 12.4h.

What is the water temperature in September in Mendocino?

In September, the average ocean temperature is 54.9°F (12.7°C). Swimming in 54.9°F (12.7°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.

How many hours of daylight does Mendocino have in September?

In September, the average length of the day is 12.4h.
Average sea temperature in September - Mendocino, CA
  • Average sea temperature in September: 54.8°F

The best month for swimming (with the highest average sea temperature) is October (55.6°F).
The coldest month (with the lowest average sea temperature) is April (52.1°F).

Average daylight in September - Mendocino, CA
  • Average daylight in September: 12.4h

The month with the longest days is June (Average daylight: 14.9h).
The month with shortest days is December (Average daylight: 9.4h).