See exactly when rain will start and stop with a minute-by-minute precipitation nowcast for the next hour.
15°
Overcast
Feels Like: 21°
Min: 13°
Max: 23°
The next few hours will be overcast, with today reaching 23°C and dropping to 23°C. The coming days will be cloudy
Compare today's weather with yesterday's data and track temperature trends over time.
Hourly Forecast
Daylight Hours
06:56
Sunrise
19:08
Sunset
Moon
Waxing Crescent
12:45
Moonrise
21:27
Moonset
Daily Forecast
Today
Thursday
Friday
Saturday
Sunday
Monday
Tuesday
Wednesday
Thursday
Friday
Air Quality Data Available
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UV Index
Humidity
Weather in Castro Valley today, September 16, 2026
Castro Valley is set for a fine, sunny day on September 16, 2026, with only limited interruptions to the clear sky. The early hours look particularly favourable for being outside. The first half of the day looks overcast, as cloud amounts reach about 100% around 01:00. Brighter weather, if it comes, waits until later.
The temperature range runs from about 13°C up to 23°C. The air stays humid, with relative humidity between 65% and 97% and the peak around 04:00. Winds stay light, near 5.5 km/h by 14:00, so the day feels still more than breezy.
Later hours favour clearer intervals, as cloud stays near 54% around 17:00. The afternoon is the better half for outdoor time. Expect visibility near 14.9 km, with poorer spells close to 12.2 km. Sunrise is at 06:56 and sunset at 19:08, giving 12 hours 11 minutes of sunlight today.
In short, September 16, 2026 looks like a fine day in Castro Valley for being outside, peaking around 23°C.
Frequently asked questions about weather in Castro Valley
How warm does it get in Castro Valley?
The warmest month in Castro Valley is August, with average high temperatures of 28°C. The average temperature during this period is around 20°C.
How cold does it get in Castro Valley?
The coldest month in Castro Valley is December, with average low temperatures of 6°C. The average temperature during this period is around 10°C.
What is the wettest time of year in Castro Valley?
The wettest month in Castro Valley is January, with an average of 104mm of precipitation.
What is the driest time of year in Castro Valley?
The driest month in Castro Valley is July, with an average of 0mm of precipitation.
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