Alto, CA Weather & Growing Conditions

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

Overnight

54°F

Partly Cloudy

Partly cloudy, with a low around 54. Southwest wind around 2 mph.

7-day forecast for Alto

When	Temp	Forecast	Wind	Precip
Overnight	54°F	Partly Cloudy	2 mph SW	1%
Tuesday	80°F	Haze then Sunny	3 to 7 mph SW	1%
Tuesday Night	55°F	Partly Cloudy then Patchy Fog	2 mph SW	2%
Wednesday	80°F	Mostly Sunny	2 to 6 mph SW	2%
Wednesday Night	55°F	Partly Cloudy then Patchy Fog	2 mph SSW	0%
Thursday	82°F	Patchy Fog then Mostly Sunny	0 to 5 mph SW	0%
Thursday Night	56°F	Mostly Clear	0 to 3 mph SW	0%
Friday	88°F	Sunny	1 to 6 mph WSW	0%
Friday Night	57°F	Mostly Clear	1 to 6 mph WSW	0%
Saturday	86°F	Sunny	1 to 6 mph SW	0%
Saturday Night	58°F	Mostly Clear	5 mph WSW	0%
Sunday	84°F	Sunny	2 to 9 mph WSW	0%
Sunday Night	56°F	Mostly Clear	5 to 8 mph SW	0%
Monday	77°F	Sunny	5 to 9 mph SW	0%

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 Aug 4, 2026.