Harman US

Fort Smith, MT Weather & Growing Conditions

Local forecast, frost dates, hardiness zone and planting guidance for Fort Smith, a community in Big Horn County, Montana.

This Afternoon
61°F
Showers And Thunderstorms
Showers and thunderstorms. Cloudy. High near 61, with temperatures falling to around 58 in the afternoon. Northwest wind around 13 mph. Chance of precipitation is 90%.

7-day forecast for Fort Smith

WhenTempForecastWindPrecip
This Afternoon 61°F Showers And Thunderstorms 13 mph NW 85%
Tonight 49°F Patchy Fog 12 to 16 mph WNW 88%
Sunday 62°F Rain Showers 8 to 12 mph WNW 75%
Sunday Night 47°F Chance Rain Showers then Patchy Fog 3 mph WSW 41%
Monday 71°F Patchy Fog then Mostly Sunny 1 to 6 mph SSE 3%
Monday Night 48°F Mostly Clear 7 mph S 0%
Tuesday 79°F Sunny 2 to 6 mph ESE 1%
Tuesday Night 54°F Partly Cloudy 6 mph S 7%
Wednesday 79°F Partly Sunny 6 mph W 8%
Wednesday Night 54°F Mostly Clear 3 to 12 mph S 3%
Thursday 83°F Sunny 7 to 10 mph SW 1%
Thursday Night 55°F Mostly Clear 3 to 9 mph SSE 2%
Friday 83°F Mostly Sunny 8 mph SSW 1%
Friday Night 54°F Partly Cloudy 5 to 12 mph S 7%

Forecast source: National Weather Service (api.weather.gov) for Fort Smith (45.317, -107.935). Updated through the day.

Growing snapshot for Fort Smith

Last spring frost
May 7
First fall frost
Oct 5
Growing season
151 days
Hardiness zone
5a

More local growing data for Fort Smith: nearby ZIP 59035 weather · frost dates · planting calendar · Montana frost dates

Nearby towns & communities

All Montana locations ›

Climate data from the nearest NOAA station, Yellowtail Dam, Mt (0.8 mi from Fort Smith). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 20, 2026.