Alto, CA Weather & Growing Conditions

Local forecast, frost dates, hardiness zone and planting guidance for Alto, a community in Marin County, California.

This Afternoon

63°F

Light Rain

Rain. Mostly cloudy. High near 63, with temperatures falling to around 59 in the afternoon. South southwest wind 0 to 7 mph. Chance of precipitation is 90%. New rainfall amounts between a tenth and quarter of an inch possible.

7-day forecast for Alto

When	Temp	Forecast	Wind	Precip
This Afternoon	63°F	Light Rain	0 to 7 mph SSW	90%
Tonight	49°F	Chance Light Rain then Mostly Cloudy	1 to 7 mph E	44%
Wednesday	67°F	Sunny	2 to 7 mph N	3%
Wednesday Night	50°F	Partly Cloudy	1 to 7 mph NW	0%
Thursday	71°F	Sunny	2 mph NNW	0%
Thursday Night	50°F	Mostly Clear	1 mph NNW	0%
Friday	72°F	Sunny	1 mph N	0%
Friday Night	50°F	Mostly Clear	1 mph N	0%
Saturday	76°F	Sunny	0 to 6 mph NNE	0%
Saturday Night	51°F	Mostly Clear	2 mph NW	0%
Sunday	74°F	Mostly Sunny	3 mph NNW	0%
Sunday Night	53°F	Partly Cloudy	1 mph NW	0%
Monday	72°F	Partly Sunny	3 mph WNW	1%
Monday Night	51°F	Partly Cloudy	2 mph NW	2%

Forecast source: National Weather Service (api.weather.gov) for Alto (37.906, -122.519). Updated through the day.

Growing snapshot for Alto

Last spring frost

Jan 16

First fall frost

Dec 18

Growing season

334 days

Hardiness zone

10a

More local growing data for Alto: nearby ZIP 94925 weather · frost dates · planting calendar · California frost dates

Nearby towns & communities

Belvedere Black Point-Green Point Bolinas Corte Madera Dillon Beach Fairfax Inverness Kentfield Lagunitas-Forest Knolls Larkspur Lucas Valley-Marinwood Marin City Mill Valley Muir Beach Nicasio Novato Petaluma Center Point Reyes Station Ross San Anselmo San Francisco San Geronimo San Rafael Santa Venetia Sausalito Sleepy Hollow Stinson Beach Strawberry Tamalpais-Homestead Valley Tiburon

All California locations ›

Climate data from the nearest NOAA station, Kentfield, Ca (2.6 mi from Alto). Frost dates are 1991–2020 averages, not a forecast. Page updated Nov 4, 2026.