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
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| 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
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.