Castro Valley, CA Weather Forecast for 5-Days

Updated: Thu Dec 11th 2025 4:45 AM PST

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Castro Valley, CA Weather – 12-11 – Sunny
71° / 42°
Sunny
Highs will reach 71°F with lows near 42°F in Castro Valley, where a sunny day is. Winds will be light at 4mph and gusts of 7mph at 5 AM. The humidity will be on the higher side, averaging about 65%, the maximum being 75% at 10 PM and 46% being its lowest at 3 PM. Barometric pressure is its highest of 30.12inHg at 10 AM, a lowest point of 30.03inHg at 4 PM with an avg 30.07inHg.
Castro Valley, CA Weather – 12-12 – Sunny
69° / 49°

Weather Tomorrow

Sunny
Daytime highs will reach 69°F with lows dropping to 49°F in Castro Valley, where it will be sunny. Winds will be light at 4mph and gusts of 7.5mph at 7 AM. Humidity levels should be comfortable, sitting around 58% on average, the maximum being 76% at 10 PM and 40% being its lowest at 2 PM. Barometric pressure is its highest of 30.06inHg at 11 PM, a lowest point of 29.99inHg at 5 PM with an avg 30.03inHg.
Castro Valley, CA Weather – 12-13 – Sunny
70° / 47°
Sunny
Castro Valley may see sunshine, with daytime highs of 70°F and overnight lows near 47°F. Winds will be light at 4mph and gusts of 7mph at 7 AM. The humidity will be on the higher side, averaging about 64%, the maximum being 87% at 5 AM and 45% being its lowest at 2 PM. Barometric pressure is its highest of 30.06inHg at 11 AM, a lowest point of 29.98inHg at 6 PM with an avg 30.02inHg.
Castro Valley, CA Weather – 12-14 – Sunny
66° / 50°
Sunny
Castro Valley is set for sunshine with temperatures peaking at 66°F and dipping to 50°F. Winds will be light at 4mph and gusts of 8mph at 9 PM. Humidity levels should be comfortable, sitting around 54% on average, the maximum being 66% at 8 AM and 38% being its lowest at 3 PM. Barometric pressure is its highest of 30.13inHg at 10 PM, a lowest point of 30.02inHg at 5 AM with an avg 30.07inHg.
Castro Valley, CA Weather – 12-15 – Sunny
64° / 51°
Sunny
In Castro Valley, bright and sunny conditions with highs near 64°F and lows around 51°F. Winds will be light at 4mph and gusts of 8mph at 12 AM. Humidity levels should be comfortable, sitting around 53% on average, the maximum being 62% at 8 AM and 39% being its lowest at 2 PM. Barometric pressure is its highest of 30.22inHg at 11 PM, a lowest point of 30.11inHg at 2 AM with an avg 30.17inHg.
Castro Valley, CA Weather – 12-16 – Cloudy
64° / 53°
Cloudy
It will be cloudy in Castro Valley, with a high of 64°F and a low of 53°F. Winds will be light at 5mph and gusts of 6mph at 5 PM. The humidity will be on the higher side, averaging about 73%, the maximum being 91% at 11 PM and 52% being its lowest at 12 AM. Barometric pressure is its highest of 30.28inHg at 11 AM, a lowest point of 30.19inHg at 5 PM with an avg 30.23inHg.

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