Harman US

Sweet Grass, MT Weather & Growing Conditions

Local forecast, frost dates, hardiness zone and planting guidance for Sweet Grass, a community in Toole County, Montana.

This Afternoon
47°F
Mostly Sunny
Mostly sunny. High near 47, with temperatures falling to around 41 in the afternoon. South wind 8 to 13 mph, with gusts as high as 20 mph.

7-day forecast for Sweet Grass

WhenTempForecastWindPrecip
This Afternoon 47°F Mostly Sunny 8 to 13 mph S 0%
Tonight 30°F Mostly Cloudy 8 mph WSW 0%
Wednesday 46°F Patchy Fog then Mostly Sunny 6 mph NNW 0%
Wednesday Night 30°F Mostly Clear 3 to 12 mph S 0%
Thursday 52°F Mostly Sunny 12 to 20 mph SW 0%
Thursday Night 33°F Partly Cloudy 12 to 15 mph WSW 0%
Friday 51°F Mostly Sunny 12 to 23 mph SW 5%
Friday Night 35°F Partly Cloudy 15 to 24 mph WSW 5%
Saturday 51°F Mostly Sunny 9 to 15 mph WSW 1%
Saturday Night 36°F Mostly Cloudy 9 to 15 mph SW 0%
Sunday 57°F Partly Sunny 15 to 22 mph SW 1%
Sunday Night 36°F Mostly Cloudy 9 to 18 mph WSW 2%
Monday 50°F Partly Sunny 9 to 13 mph SW 2%
Monday Night 36°F Mostly Cloudy 13 mph SSW 2%

Forecast source: National Weather Service (api.weather.gov) for Sweet Grass (48.993, -111.967). Updated through the day.

Growing snapshot for Sweet Grass

Last spring frost
May 17
First fall frost
Sep 25
Growing season
129 days
Hardiness zone
4a

More local growing data for Sweet Grass: nearby ZIP 59482 weather · frost dates · planting calendar · Montana frost dates

Nearby towns & communities

All Montana locations ›

Climate data from the nearest NOAA station, Sunburst 8 E, Mt (5.9 mi from Sweet Grass). Frost dates are 1991–2020 averages, not a forecast. Page updated Nov 4, 2026.