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Alta Sierra, CA Weather & Growing Conditions

Local forecast, frost dates, hardiness zone and planting guidance for Alta Sierra, a community in Nevada County, California.

This Afternoon
84°F
Sunny
Sunny, with a high near 84. West southwest wind around 6 mph.

7-day forecast for Alta Sierra

WhenTempForecastWindPrecip
This Afternoon 84°F Sunny 6 mph WSW 0%
Tonight 57°F Mostly Clear 5 mph ENE 0%
Sunday 83°F Partly Sunny 5 mph SSW 0%
Sunday Night 58°F Mostly Cloudy 2 mph ENE 0%
Monday 82°F Mostly Sunny 1 to 6 mph SE 0%
Monday Night 56°F Mostly Clear 0 to 5 mph E 0%
Tuesday 82°F Sunny 0 to 6 mph WSW 0%
Tuesday Night 56°F Mostly Clear 3 mph ESE 0%
Wednesday 86°F Sunny 1 to 5 mph W 0%
Wednesday Night 58°F Mostly Clear 3 mph NNW 0%
Thursday 90°F Sunny 2 to 6 mph SSW 0%
Thursday Night 59°F Mostly Clear 5 mph ESE 0%
Friday 86°F Sunny 6 mph SSE 0%
Friday Night 58°F Mostly Clear 5 mph SSE 1%

Forecast source: National Weather Service (api.weather.gov) for Alta Sierra (39.126, -121.049). Updated through the day.

Growing snapshot for Alta Sierra

Last spring frost
Apr 10
First fall frost
Nov 13
Growing season
215 days
Hardiness zone
9b

More local growing data for Alta Sierra: nearby ZIP 95949 weather · frost dates · planting calendar · California frost dates

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Climate data from the nearest NOAA station, Grass Valley #2, Ca (7.8 mi from Alta Sierra). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.