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7 Days
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Monthly
Precipitation
Temperature
Wind
Temperature Unit Selection
°Celsius
°Fahrenheit
Monthly Historical Averages
Castro Valley, CA
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May
Average Temperature
High
21°
Feels 21
Low
10°
Feels 9
Average Precipitation
3 Days
Rain amount
8.9mm
Snow amount
0cm
Daily Historical Averages
May 2026
S
M
T
W
T
F
S
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
28°
21
24°
22
23°
23
22°
24
18°
25
17°
26
19°
27
20°
28
21°
29
20°
30
20°
31
21°
Forecast
Wednesday, May 20, 2026
Day
28°
Feels 28
Wind
17 km/h W
Gust
26 km/h
Humidity
22%
P.O.P
20%
Night
12°
Feels 12
Wind
10 km/h W
Gust
16 km/h
Humidity
85%
P.O.P
0%
Historical Averages
May 20
High
Feels
Low
Feels
Precip Frequency
Total Daylight
Humidity
Historical Averages are based on data recorded from 2000 onwards.