Climate and monthly weather forecastFoster City, CA
Climate and monthly weather forecast
Weather in January
January, the same as December, in Foster City, California, is another mild winter month, with temperature in the range of an average high of 56.8°F (13.8°C) and an average low of 46.9°F (8.3°C). The start of January sees the average high-temperature at a still mild 56.8°F (13.8°C), showing little difference from December's 55.8°F (13.2°C). Weather in January »Weather in February
February, the last month of the winter in Foster City, is another refreshing month, with an average temperature fluctuating between 47.1°F (8.4°C) and 57.7°F (14.3°C). Foster City notes an average high-temperature of a still moderate 57.7°F (14.3°C) in February, hardly diverging from January. Weather in February »Weather in March
March, the first month of the spring in Foster City, is still a refreshing month, with temperature in the range of an average low of 47.7°F (8.7°C) and an average high of 59.2°F (15.1°C). An average high-temperature of a still moderate 59.2°F (15.1°C) marks March, exhibiting a close resemblance to the conditions in February. Weather in March »Weather in April
April in Foster City, California, is a comfortable spring month, with an average temperature fluctuating between 48.7°F (9.3°C) and 62.2°F (16.8°C). The arrival of April sees an average high-temperature of a still refreshing 62.2°F (16.8°C), hardly diverging from March's 59.2°F (15.1°C). Weather in April »Weather in May
May, the last month of the spring in Foster City, is also an enjoyable month, with temperature in the range of an average low of 50.7°F (10.4°C) and an average high of 63.9°F (17.7°C). The advent of May signifies a minor shift to an average high-temperature of a still comfortable 63.9°F (17.7°C), aligning closely with April. Weather in May »Weather in June
The first month of the summer, June, is an agreeable month in Foster City, California, with an average temperature ranging between min 53.4°F (11.9°C) and max 68.5°F (20.3°C). Foster City's entry into June measures an average high-temperature of a pleasant 68.5°F (20.3°C), closely parallel to the preceding month. Weather in June »Weather in July
July, the same as June, in Foster City, California, is an agreeable summer month, with an average temperature varying between 70.9°F (21.6°C) and 54.7°F (12.6°C). The arrival of July brings an average high-temperature of a still agreeable 70.9°F (21.6°C), nearly identical to June's 68.5°F (20.3°C). Weather in July »Weather in August
The last month of the summer, August, is another pleasant month in Foster City, California, with temperature in the range of an average low of 56.3°F (13.5°C) and an average high of 71.2°F (21.8°C). August and September, when the average high-temperature reaches 71.2°F (21.8°C), are the warmest months. Weather in August »Weather in September
September, the first month of the autumn in Foster City, is still a pleasant month, with an average temperature ranging between min 56.7°F (13.7°C) and max 71.2°F (21.8°C). The warmest months are August and September, with an average high-temperature of 71.2°F (21.8°C). Weather in September »Weather in October
October, like September, in Foster City, California, is another comfortable autumn month, with an average temperature fluctuating between 55.2°F (12.9°C) and 67.8°F (19.9°C). The commencement of October introduces an average high-temperature of an enjoyable 67.8°F (19.9°C), closely mirroring the preceding month. Weather in October »Weather in November
November, the last month of the autumn in Foster City, is also an enjoyable month, with temperature in the range of an average high of 61.3°F (16.3°C) and an average low of 50.9°F (10.5°C). In Foster City, the beginning of November is marked by a marginally lowered average high-temperature, shifting from October's refreshing 67.8°F (19.9°C) to a still enjoyable 61.3°F (16.3°C). Weather in November »Weather in December
December, the first month of the winter in Foster City, is still a mild month, with temperature in the range of an average low of 47.5°F (8.6°C) and an average high of 55.8°F (13.2°C). In Foster City, the month of December registers the lowest temperatures, averaging 55.8°F (13.2°C) at the peak and 47.5°F (8.6°C) at the lowest. Weather in December »Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature
Foster City, CA
The warmest months (with the highest average high temperature) are August and September (71.2°F).
The month with the lowest average high temperature is December (55.8°F).
The month with the highest average low temperature is September (56.7°F).
The coldest month (with the lowest average low temperature) is January (46.9°F).
Average pressure
Foster City, CA
- Average pressure in January:
30.13"Hg - Average pressure in February:
30.08"Hg - Average pressure in March:
30.07"Hg - Average pressure in April:
30.04"Hg - Average pressure in May:
29.98"Hg - Average pressure in June:
29.93"Hg
- Average pressure in July:
29.93"Hg - Average pressure in August:
29.93"Hg - Average pressure in September:
29.92"Hg - Average pressure in October:
29.99"Hg - Average pressure in November:
30.07"Hg - Average pressure in December:
30.11"Hg
The month with the highest atmospheric pressure is January (30.13"Hg).
The month with the lowest atmospheric pressure is September (29.92"Hg).
Average wind speed
Foster City, CA
- Average wind speed in January:
6.2mph - Average wind speed in February:
7.4mph - Average wind speed in March:
7.7mph - Average wind speed in April:
8mph - Average wind speed in May:
7.8mph - Average wind speed in June:
7.2mph
- Average wind speed in July:
6mph - Average wind speed in August:
5.9mph - Average wind speed in September:
5.9mph - Average wind speed in October:
5.9mph - Average wind speed in November:
6mph - Average wind speed in December:
6.9mph
The windiest month (with the highest average wind speed) is April (8mph).
The calmest months (with the lowest average wind speed) are August, September and October (5.9mph).
Average humidity
Foster City, CA
The months with the highest relative humidity are March and August (76%).
The months with the lowest relative humidity are October and November (70%).
Average rainfall
Foster City, CA
- Average rainfall in January:
0.31" - Average rainfall in February:
0.55" - Average rainfall in March:
0.35" - Average rainfall in April:
0.08" - Average rainfall in May:
0.16" - Average rainfall in June:
0"
The wettest month (with the highest rainfall) is February (0.55").
The driest months (with the least rainfall) are June, July and August (0").
Average rainfall days
Foster City, CA
- Average rainfall days in January:
4.4 days - Average rainfall days in February:
3.2 days - Average rainfall days in March:
6.8 days - Average rainfall days in April:
3.8 days - Average rainfall days in May:
2.5 days - Average rainfall days in June:
0.4 days
- Average rainfall days in July:
0.3 days - Average rainfall days in August:
0.7 days - Average rainfall days in September:
0.9 days - Average rainfall days in October:
1.4 days - Average rainfall days in November:
2.7 days - Average rainfall days in December:
5.5 days
The month with the highest number of rainy days is March (6.8 days).
The month with the least rainy days is July (0.3 days).
Average daylight / Average sunshine
Foster City, CA
- Average daylight in January:
9h and 54min - Average daylight in February:
10h and 48min - Average daylight in March:
12h and 0min - Average daylight in April:
13h and 12min - Average daylight in May:
14h and 12min - Average daylight in June:
14h and 42min
- Average daylight in July:
14h and 30min - Average daylight in August:
13h and 36min - Average daylight in September:
12h and 24min - Average daylight in October:
11h and 12min - Average daylight in November:
10h and 12min - Average daylight in December:
9h and 36min
The month with the longest days is June (Average daylight: 14h and 42min).
The month with the shortest days is December (Average daylight: 9h and 36min).
- Average sunshine in January:
6h and 12min - Average sunshine in February:
6h and 18min - Average sunshine in March:
7h and 54min - Average sunshine in April:
10h and 18min - Average sunshine in May:
10h and 42min - Average sunshine in June:
11h and 36min
- Average sunshine in July:
12h and 0min - Average sunshine in August:
11h and 48min - Average sunshine in September:
11h and 0min - Average sunshine in October:
7h and 6min - Average sunshine in November:
6h and 36min - Average sunshine in December:
5h and 54min
The month with the most sunshine is July (Average sunshine: 12h and 0min).
The month with the least sunshine is December (Average sunshine: 5h and 54min).
Average sunshine days
Foster City, CA
- Average sunshine days in January:
25 days - Average sunshine days in February:
23.3 days - Average sunshine days in March:
23.8 days - Average sunshine days in April:
25.4 days - Average sunshine days in May:
27.6 days - Average sunshine days in June:
29.3 days
- Average sunshine days in July:
30.4 days - Average sunshine days in August:
30.2 days - Average sunshine days in September:
28.7 days - Average sunshine days in October:
28.8 days - Average sunshine days in November:
26.3 days - Average sunshine days in December:
24.4 days
The month with the most sunshine days is July (30.4 days).
The month with the least sunshine days is February (23.3 days).
Average UV index
Foster City, CA
The months with the highest UV index are June, July, August and September (UV index 5).
The months with the lowest UV index are February and December (UV index 3).
Average cloud cover
Foster City, CA
The month with the most cloud cover is March (Cloud cover 35).
The month with the least cloud cover is July (Cloud cover 11).
Average visibility
Foster City, CA
The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).





