Annual mean 14°C · wettest around March · prevailing wind NW
Warmest
21.2 °C
Coldest
12.9 °C
Wettest
62%
Windiest
5.2 m/s
Prevailing
NW
4.3 m/s average
When this place is good five ratings · thirty-six ten-day sections · click a cell to read it
never good
never good
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Every reading
bars actual · line feels-like, °Cchance of rain, %wind speed, m/ssky covered, %
The average temperature in Foster City over the whole year is 14°C. September is the hottest month, with highs of about 21°C; February is the coldest, with lows of about 8°C. The rainy (wet) season in Foster City runs from October to May, peaking in March with a 63% chance of rain on a given day. The dry season is June to September; June is the driest month, at 21%. Winds in Foster City are highest in May, averaging 3.8 m/s (14 km/h), and lightest in November, at 2.4 m/s (9 km/h). The prevailing wind is from the NW. The clearest skies in Foster City come in October, when the sky is typically 37% covered; August is the cloudiest month, at 52%.
Month by month Foster City climate by month: average temperatures year round · click a month to read it
Month
High
Low
Feels like
Chance of rain
Cloud
Wind
Being outside
Sun
Walking
January
13°C
9°C
10°C
62%
52%
2.8 m/s
13
0
74
February
14°C
8°C
10°C
62%
40%
3.2 m/s
19
0
70
March
14°C
9°C
11°C
63%
51%
3.4 m/s
18
0
73
April
16°C
10°C
13°C
58%
45%
3.6 m/s
31
2
79
May
17°C
12°C
14°C
55%
49%
3.8 m/s
39
4
80
June
19°C
14°C
17°C
21%
43%
3.8 m/s
49
10
76
July
19°C
14°C
18°C
38%
51%
3.5 m/s
60
13
74
August
20°C
15°C
19°C
35%
52%
3.2 m/s
72
15
71
September
21°C
14°C
19°C
33%
44%
3.0 m/s
70
14
73
October
20°C
12°C
17°C
52%
37%
2.5 m/s
65
9
77
November
16°C
9°C
13°C
58%
38%
2.4 m/s
36
0
83
December
14°C
9°C
11°C
62%
45%
2.5 m/s
14
0
75
High and low are the warmest and coolest of four readings a day — midnight, 6am, noon and 6pm — so a true overnight low can sit a degree or two under them. Chance of rain, cloud and wind are the day’s average; feels-like and the three ratings (each out of 100: Good from 55, Ideal from 80) are read at midday.
Seasons, and the year in short Foster City weather by season
Year round, Foster City has days of about 13°C at their warmest in January, its coolest month, and 21°C in September, its warmest; the coolest hours of the day run from 8°C to 15°C through the year, and the average temperature over the year is 14°C around the clock. Rain is most likely around March and least likely around June. Every figure here is a decade of observations blended into one representative year, so it reads as what this date is usually like, not a forecast for one particular day.
Foster City weather in winterDecember to February
High 14°CLow 8°CRain 62%
Winter in Foster City has typical daily highs of about 14°C and lows of about 8°C, with a 62% chance of rain on a given day.
Foster City weather in springMarch to May
High 16°CLow 10°CRain 59%
Spring in Foster City has typical daily highs of about 16°C and lows of about 10°C, with a 59% chance of rain on a given day.
Foster City weather in summerJune to August
High 19°CLow 14°CRain 31%
Summer in Foster City has typical daily highs of about 19°C and lows of about 14°C, with a 31% chance of rain on a given day.
Foster City weather in autumnSeptember to November
High 19°CLow 12°CRain 48%
Autumn in Foster City has typical daily highs of about 19°C and lows of about 12°C, with a 48% chance of rain on a given day.
When is the rainy season in Foster City?
The rainy (wet) season in Foster City runs from October to May, peaking in March with a 63% chance of rain on a given day. The dry season is June to September; June is the driest month, at 21%.
What time of year is Foster City windiest?
Winds in Foster City are highest in May, averaging 3.8 m/s (14 km/h), and lightest in November, at 2.4 m/s (9 km/h). The prevailing wind is from the NW.
What is the average temperature in Foster City year round?
The average temperature in Foster City over the whole year is 14°C. September is the hottest month, with highs of about 21°C; February is the coldest, with lows of about 8°C.