Current Conditions

Castro Valley, California

54°F12°C

Clear

Wind

SSW 3 mph5 km/h

Humidity

95%

Cloud Cover

83%

As of Wednesday, September 23, 2026 at 3:36 AM PDT

Today's Outlook

Day

Mostly clear and warm, with a high of 82°F28°C and morning low of 56°F13°C. Light wind from the WNW around 3 mph5 km/h.

Night

Partly cloudy, with a low around 54°F12°C. Light wind from the SW around 3 mph5 km/h.

7-Day Forecast

Condition	High (°F)	Low (°F)	Precip (mm)	Cloud Cover (%)	Wind (mph)
Clear	High 82°F28°C	Low 54°F12°C	Precip 0 in0 mm—	Cloud 30%	Wind WSW 3 mph5 km/h	Wednesday: Mostly clear and warm, with a high of 82°F28°C and morning low of 56°F13°C. Light wind from the WNW around 3 mph5 km/h. Wednesday Night: Partly cloudy, with a low around 54°F12°C. Light wind from the SW around 3 mph5 km/h.
Partly Cloudy	High 81°F27°C	Low 57°F14°C	Precip 0 in0 mm—	Cloud 60%	Wind WSW 4 mph7 km/h	Thursday: Mostly cloudy and warm, with a high of 81°F27°C and morning low of 58°F14°C. Breezy from the WSW at 5 to 8 mph8 to 13 km/h. Thursday Night: Mostly cloudy, with a low around 57°F14°C. Light wind from the SW around 4 mph6 km/h.
Clear	High 76°F24°C	Low 57°F14°C	Precip 0 in0 mm—	Cloud 25%	Wind WSW 6 mph9 km/h	Friday: Mostly clear and warm, with a high of 76°F24°C and morning low of 61°F16°C. Breezy from the W at 7 to 9 mph12 to 15 km/h. Friday Night: Partly cloudy, with a low around 57°F14°C. Light wind from the SW around 4 mph7 km/h.
Clear	High 74°F24°C	Low 53°F12°C	Precip 0 in0 mm—	Cloud 38%	Wind WSW 5 mph7 km/h	Saturday: Partly cloudy and warm, with a high of 74°F24°C and morning low of 55°F13°C. Breezy from the WSW at 5 to 7 mph8 to 12 km/h. Saturday Night: Partly cloudy, with a low around 53°F12°C. Light wind from the SW around 4 mph6 km/h.
Partly Cloudy	High 70°F21°C	Low 54°F12°C	Precip 0 in0.1 mm2%	Cloud 44%	Wind SW 6 mph10 km/h	Sunday: Partly cloudy and warm, with a high of 70°F21°C and morning low of 56°F13°C. Breezy from the WSW at 7 to 8 mph11 to 13 km/h. Sunday Night: Partly cloudy, with a low around 54°F12°C. Light wind from the SW around 5 mph8 km/h.
Clear	High 74°F23°C	Low 54°F12°C	Precip 0 in0 mm—	Cloud 25%	Wind WSW 4 mph7 km/h	Monday: Mostly clear and warm, with a high of 74°F23°C and morning low of 56°F13°C. Breezy from the W at 5 to 7 mph8 to 12 km/h. Monday Night: Partly cloudy, with a low around 54°F12°C. Light wind from the SW around 4 mph6 km/h.
Clear	High 79°F26°C	Low 55°F13°C	Precip 0 in0 mm—	Cloud 14%	Wind WSW 4 mph6 km/h	Tuesday: Mostly clear and warm, with a high of 79°F26°C and morning low of 57°F14°C. Light wind from the W around 4 mph7 km/h. Tuesday Night: Mostly clear, with a low around 55°F13°C. Light wind from the SW around 4 mph6 km/h.

15-Day Forecast

	Day	High	Low	Precip	Cloud Cover	Condition	Wind
	WednesdaySep 23	82°F28°C	54°F12°C	0 in0 mm· —	30%	Clear	WSW 3 mph5 km/h
DayMostly clear and warm, with a high of 82°F28°C and morning low of 56°F13°C. Light wind from the WNW around 3 mph5 km/h. NightPartly cloudy, with a low around 54°F12°C. Light wind from the SW around 3 mph5 km/h.
	ThursdaySep 24	81°F27°C	57°F14°C	0 in0 mm· —	60%	Partly Cloudy	WSW 4 mph7 km/h
DayMostly cloudy and warm, with a high of 81°F27°C and morning low of 58°F14°C. Breezy from the WSW at 5 to 8 mph8 to 13 km/h. NightMostly cloudy, with a low around 57°F14°C. Light wind from the SW around 4 mph6 km/h.
	FridaySep 25	76°F24°C	57°F14°C	0 in0 mm· —	25%	Clear	WSW 6 mph9 km/h
DayMostly clear and warm, with a high of 76°F24°C and morning low of 61°F16°C. Breezy from the W at 7 to 9 mph12 to 15 km/h. NightPartly cloudy, with a low around 57°F14°C. Light wind from the SW around 4 mph7 km/h.
	SaturdaySep 26	74°F24°C	53°F12°C	0 in0 mm· —	38%	Clear	WSW 5 mph7 km/h
DayPartly cloudy and warm, with a high of 74°F24°C and morning low of 55°F13°C. Breezy from the WSW at 5 to 7 mph8 to 12 km/h. NightPartly cloudy, with a low around 53°F12°C. Light wind from the SW around 4 mph6 km/h.
	SundaySep 27	70°F21°C	54°F12°C	0 in0.1 mm· 2%	44%	Partly Cloudy	SW 6 mph10 km/h
DayPartly cloudy and warm, with a high of 70°F21°C and morning low of 56°F13°C. Breezy from the WSW at 7 to 8 mph11 to 13 km/h. NightPartly cloudy, with a low around 54°F12°C. Light wind from the SW around 5 mph8 km/h.
	MondaySep 28	74°F23°C	54°F12°C	0 in0 mm· —	25%	Clear	WSW 4 mph7 km/h
DayMostly clear and warm, with a high of 74°F23°C and morning low of 56°F13°C. Breezy from the W at 5 to 7 mph8 to 12 km/h. NightPartly cloudy, with a low around 54°F12°C. Light wind from the SW around 4 mph6 km/h.
	TuesdaySep 29	79°F26°C	55°F13°C	0 in0 mm· —	14%	Clear	WSW 4 mph6 km/h
DayMostly clear and warm, with a high of 79°F26°C and morning low of 57°F14°C. Light wind from the W around 4 mph7 km/h. NightMostly clear, with a low around 55°F13°C. Light wind from the SW around 4 mph6 km/h.
	WednesdaySep 30	81°F27°C	57°F14°C	0.01 in0.2 mm· 3%	29%	Clear	WSW 4 mph6 km/h
DayPartly cloudy and warm, with a high of 81°F27°C and morning low of 58°F14°C. Light wind from the W around 4 mph6 km/h. NightPartly cloudy, with a low around 57°F14°C. Light wind from the SW around 3 mph5 km/h.
	ThursdayOct 1	79°F26°C	58°F14°C	0.01 in0.2 mm· 2%	43%	Partly Cloudy	WSW 4 mph7 km/h
DayPartly cloudy and warm, with a high of 79°F26°C and morning low of 59°F15°C. Light wind from the W around 5 mph7 km/h. NightPartly cloudy, with a low around 58°F14°C. Light wind from the SW around 4 mph6 km/h.
	FridayOct 2	80°F27°C	57°F14°C	0.01 in0.2 mm· 2%	25%	Clear	W 4 mph6 km/h
DayMostly clear and warm, with a high of 80°F27°C and morning low of 59°F15°C. Light wind from the WNW around 4 mph7 km/h. NightPartly cloudy, with a low around 57°F14°C. Light wind from the SW around 3 mph6 km/h.
	SaturdayOct 3	82°F28°C	58°F14°C	0 in0.1 mm· 2%	17%	Clear	W 4 mph7 km/h
DayMostly clear and warm, with a high of 82°F28°C and morning low of 59°F15°C. Light wind from the NW around 5 mph7 km/h. Dry air. NightMostly clear, with a low around 58°F14°C. Light wind from the SW around 4 mph6 km/h.
	SundayOct 4	81°F27°C	59°F15°C	0 in0.1 mm· 1%	22%	Clear	W 4 mph7 km/h
DayMostly clear and warm, with a high of 81°F27°C and morning low of 60°F15°C. Light wind from the WNW around 4 mph7 km/h. Dry air. NightMostly clear, with a low around 59°F15°C. Light wind from the SW around 4 mph6 km/h.
	MondayOct 5	81°F27°C	59°F15°C	0 in0.1 mm· 2%	21%	Clear	WSW 4 mph6 km/h
DayMostly clear and warm, with a high of 81°F27°C and morning low of 59°F15°C. Light wind from the WNW around 4 mph7 km/h. NightMostly clear, with a low around 59°F15°C. Light wind from the SW around 3 mph5 km/h.
	TuesdayOct 6	81°F27°C	59°F15°C	0 in0 mm· —	22%	Clear	WSW 4 mph6 km/h
DayMostly clear and warm, with a high of 81°F27°C and morning low of 60°F16°C. Light wind from the W around 4 mph7 km/h. NightMostly clear, with a low around 59°F15°C. Light wind from the SW around 3 mph6 km/h.
	WednesdayOct 7	80°F27°C	59°F15°C	0.02 in0.5 mm· 4%	24%	Clear	WSW 4 mph7 km/h
DayMostly clear and warm, with a high of 80°F27°C and morning low of 60°F16°C. Light wind from the W around 5 mph8 km/h. NightPartly cloudy, with a low around 59°F15°C. Light wind from the SW around 4 mph6 km/h.

Nearby Cities

Ashland2 mi2 km Hayward2 mi3 km San Lorenzo3 mi5 km San Leandro4 mi7 km Union City8 mi12 km Dublin8 mi13 km

About This Forecast

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Coordinates: 37.6941°N, 122.0863°W·Elevation: 50m·Timezone: America/Los_Angeles·Population: 61,388