. In fact, both the winter temperatures and the rain pattern remind of the Mediterranean climate, but summer is unusually cool because of the
that flows along the coast of California and is able to keep the temperatures low.
, of San Francisco, across the bay, and is the county seat of Alameda county. Compared to San Francisco, the city is less exposed to fogs from the ocean on summer mornings. However, the most exposed areas are the northern one, towards Berkeley, and the eastern one, towards the hills.
, there can be very mild days, with highs of 18/20 °C (64/68 °F).
of the year, the temperature generally drops to around freezing, while during the day it remains around 10 °C (50 °F). Real cold spells are very rare, for example, in December 1990, it dropped to -4.3 °C (37 °F), with only 4 °C (39 °F) as maximum temperature. Snow is extremely rare; in February 1976, it snowed, although with temperatures above freezing.
of the year, the temperature usually reaches 33/35 °C (91/95 °F), and this happens more easily in September or early October, when a hot wind can blow from the desert, similar to the Santa Ana winds of the Los Angeles area, but less intense. On September 1, 2017, it reached 38.3 °C (37 °F).
, from June to September, since it is the driest and warmest season of the year. However, you have to take into account cool temperatures, and sometimes even a little cold, at night and in the early morning, as well as morning fogs, so it's better to bring a jacket and a sweater.
Usually, in the months of April, May and October, the weather is good as well, in fact, it's often mild and sunny, even though there's a greater chance of rain; in addition, it can get cold at night, especially in April. Moreover, in spring, afternoon breezes are quite intense.
. Here are the average temperatures.
January, the coldest month of the year, is generally a mild month. The average temperature is of
9.9 °C, with a minimum of
5.6 °C and a maximum of
14.3 °C.
On the coldest nights of the month, the temperature usually drops to around
1 °C. However, it dropped to
-2.2 °C in January 2007.
On the warmest days of the month, the temperature usually reaches around
19 °C. However, it reached
25 °C in January 2009.
Precipitation amounts to
85 mm, distributed over 10 days.
The day lasts on average 9 hours and 55 minutes.
The average humidity is 79%. Hence, the air is normally humid.
The average wind speed is of
10.6 kph.
The average sea temperature is of
12.4 °C. Therefore, the sea is very cold for swimming.
February is generally a mild month. The average temperature is of
11.4 °C, with a minimum of
7 °C and a maximum of
15.7 °C.
On the coldest nights of the month, the temperature usually drops to around
2 °C. However, it dropped to
-0.6 °C in February 2002.
On the warmest days of the month, the temperature usually reaches around
21 °C. However, it reached
27.2 °C in February 2011.
Precipitation amounts to
90 mm, distributed over 10 days.
The day lasts on average 10 hours and 50 minutes.
The average humidity is 75%. Hence, the air is normally humid.
The average wind speed is of
12.6 kph.
The average sea temperature is of
12.2 °C. Therefore, the sea is very cold for swimming.
March is generally a mild month. The average temperature is of
12.8 °C, with a minimum of
8.3 °C and a maximum of
17.3 °C.
On the coldest nights of the month, the temperature usually drops to around
4 °C. However, it dropped to
1.1 °C in March 2012.
On the warmest days of the month, the temperature usually reaches around
23.5 °C. However, it reached
30 °C in March 2004.
Precipitation amounts to
70 mm, distributed over 10 days.
The day lasts on average 12 hours and 0 minutes.
The average humidity is 73%. Hence, the air is normally humid.
The average wind speed is of
14.2 kph.
The average sea temperature is of
12.2 °C. Therefore, the sea is very cold for swimming.
April is generally a mild month. The average temperature is of
14.1 °C, with a minimum of
9.5 °C and a maximum of
18.7 °C.
On the coldest nights of the month, the temperature usually drops to around
5.5 °C. However, it dropped to
2.2 °C in April 2012.
On the warmest days of the month, the temperature usually reaches around
26.5 °C. However, it reached
32.8 °C in April 2009.
Precipitation amounts to
35 mm, distributed over 6 days.
The day lasts on average 13 hours and 10 minutes.
The average humidity is 70%. Hence, the air is normally humid.
The average wind speed is of
16 kph.
The average sea temperature is of
11.8 °C. Therefore, the sea is very cold for swimming.
May is generally a very mild month. The average temperature is of
15.5 °C, with a minimum of
11.1 °C and a maximum of
19.9 °C.
On the coldest nights of the month, the temperature usually drops to around
8 °C. However, it dropped to
5 °C in May 2010.
On the warmest days of the month, the temperature usually reaches around
29 °C. However, it reached
37.2 °C in May 2008.
Precipitation amounts to
15 mm, distributed over 3 days.
The day lasts on average 14 hours and 20 minutes. So the days are long.
The average humidity is 72%. Hence, the air is normally humid.
The average wind speed is of
16.9 kph.
The average sea temperature is of
11.8 °C. Therefore, the sea is very cold for swimming.
June is generally a very mild month. The average temperature is of
17.1 °C, with a minimum of
12.3 °C and a maximum of
21.9 °C.
On the coldest nights of the month, the temperature usually drops to around
10 °C. However, it dropped to
7.8 °C in June 2005.
On the warmest days of the month, the temperature usually reaches around
31.5 °C. However, it reached
37.8 °C in June 2000.
Precipitation amounts to only
5 mm, and all occurs in one day.
The day lasts on average 14 hours and 40 minutes. So the days are long. June 21, the summer solstice, is the longest day of the year in the Northern Hemisphere.
The average humidity is 72%. Hence, the air is normally humid.
The average wind speed is of
16.4 kph.
The average sea temperature is of
12.2 °C. Therefore, the sea is very cold for swimming.
July is generally a very mild month. The average temperature is of
17.7 °C, with a minimum of
13.4 °C and a maximum of
22 °C.
On the coldest nights of the month, the temperature usually drops to around
11.5 °C. However, it dropped to
9.4 °C in July 2000.
On the warmest days of the month, the temperature usually reaches around
30 °C. However, it reached
36 °C in July 2006.
Precipitation amounts to only
0 mm, so on average it never rains in the whole month.
The day lasts on average 14 hours and 30 minutes. So the days are long.
The average humidity is 76%. Hence, the air is normally humid.
The average wind speed is of
16.3 kph.
The average sea temperature is of
13.1 °C. Therefore, the sea is very cold for swimming.
August is generally a warm month. The average temperature is of
18.1 °C, with a minimum of
13.8 °C and a maximum of
22.4 °C.
On the coldest nights of the month, the temperature usually drops to around
11.5 °C. However, it dropped to
9 °C in August 2011.
On the warmest days of the month, the temperature usually reaches around
30.5 °C. However, it reached
38.3 °C in August 2020.
Precipitation amounts to only
0 mm, so on average it never rains in the whole month.
The day lasts on average 13 hours and 30 minutes.
The average humidity is 76%. Hence, the air is normally humid.
The average wind speed is of
15.2 kph.
The average sea temperature is of
14 °C. Therefore, the sea is very cold for swimming.
September, the warmest month of the year, is generally a warm month. The average temperature is of
18.2 °C, with a minimum of
13.1 °C and a maximum of
23.4 °C.
On the coldest nights of the month, the temperature usually drops to around
10 °C. However, it dropped to
7.8 °C in September 2005.
On the warmest days of the month, the temperature usually reaches around
32.5 °C. However, it reached
40 °C in September 2020.
Precipitation amounts to only
5 mm, distributed over 2 days.
The day lasts on average 12 hours and 25 minutes.
The average humidity is 73%. Hence, the air is normally humid.
The average wind speed is of
13.4 kph.
The average sea temperature is of
14.4 °C. Therefore, the sea is very cold for swimming.
October is generally a very mild month. The average temperature is of
16.3 °C, with a minimum of
10.7 °C and a maximum of
21.9 °C.
On the coldest nights of the month, the temperature usually drops to around
7.5 °C. However, it dropped to
4.4 °C in October 2002.
On the warmest days of the month, the temperature usually reaches around
31 °C. However, it reached
36.7 °C in October 2020.
Precipitation amounts to
20 mm, distributed over 5 days.
The day lasts on average 11 hours and 10 minutes.
The average humidity is 70%.
The average wind speed is of
11.4 kph.
The average sea temperature is of
14.2 °C. Therefore, the sea is very cold for swimming.
November is generally a mild month. The average temperature is of
12.7 °C, with a minimum of
7.7 °C and a maximum of
17.7 °C.
On the coldest nights of the month, the temperature usually drops to around
3.5 °C. However, it dropped to
-1.2 °C in November 1992.
On the warmest days of the month, the temperature usually reaches around
24 °C. However, it reached
28 °C in November 2008.
Precipitation amounts to
50 mm, distributed over 8 days.
The day lasts on average 10 hours and 5 minutes.
The average humidity is 73%. Hence, the air is normally humid.
The average wind speed is of
10.2 kph.
The average sea temperature is of
13.6 °C. Therefore, the sea is very cold for swimming.
December is generally a mild month. The average temperature is of
10.1 °C, with a minimum of
5.7 °C and a maximum of
14.4 °C.
On the coldest nights of the month, the temperature usually drops to around
1 °C. However, it dropped to
-2.2 °C in December 2013.
On the warmest days of the month, the temperature usually reaches around
19.5 °C. However, it reached
26.1 °C in December 2020.
Precipitation amounts to
100 mm, distributed over 11 days.
The day lasts on average 9 hours and 35 minutes. December 21, the winter solstice, is the shortest day of the year in the Northern Hemisphere.
The average humidity is 75%. Hence, the air is normally humid.
The average wind speed is of
11.1 kph.
The average sea temperature is of
12.7 °C. Therefore, the sea is very cold for swimming.