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Helena, MT Weather & Growing Conditions

Local forecast, frost dates, hardiness zone and planting guidance for Helena, a city in Lewis And Clark County, Montana.

Today
63°F
Patchy Fog
Patchy fog and showers and thunderstorms before 9am, then rain between 9am and noon, then showers and thunderstorms. Cloudy. High near 63, with temperatures falling to around 60 in the afternoon. Northwest wind around 5 mph. Chance of precipitation is 100%. New rainfall amounts between a half and three quarters of an inch possible.

7-day forecast for Helena

WhenTempForecastWindPrecip
Today 63°F Patchy Fog 5 mph NW 96%
Tonight 45°F Slight Chance Light Rain then Mostly Cloudy 3 mph WSW 15%
Sunday 72°F Mostly Sunny 0 to 5 mph ESE 0%
Sunday Night 44°F Mostly Clear 5 mph S 0%
Monday 76°F Sunny 1 to 8 mph S 0%
Monday Night 46°F Mostly Clear 2 to 6 mph WSW 0%
Tuesday 77°F Sunny 1 to 6 mph SSE 0%
Tuesday Night 47°F Partly Cloudy 5 mph SSW 2%
Wednesday 78°F Sunny 1 to 7 mph SSE 1%
Wednesday Night 48°F Mostly Clear 5 mph SSE 2%
Thursday 79°F Sunny 2 to 6 mph SSE 2%
Thursday Night 48°F Mostly Clear 5 mph S 4%
Friday 77°F Mostly Sunny 2 to 7 mph S 3%
Friday Night 46°F Mostly Cloudy 8 mph W 14%

Forecast source: National Weather Service (api.weather.gov) for Helena (46.595, -112.019). Updated through the day.

Growing snapshot for Helena

Last spring frost
May 9
First fall frost
Sep 30
Growing season
142 days

More local growing data for Helena: nearby ZIP 59625 weather · frost dates · planting calendar · Montana frost dates

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Climate data from the nearest NOAA station, Helena Rgnl Ap, Mt (3.6 mi from Helena). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.