Westby, MT Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Westby, a town in Sheridan County, Montana.
Tonight
54°F
Slight Chance Rain Showers then Mostly Cloudy
A slight chance of rain showers before 10pm. Mostly cloudy, with a low around 54. Northeast wind around 12 mph, with gusts as high as 18 mph. Chance of precipitation is 20%.
7-day forecast for Westby
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 54°F | Slight Chance Rain Showers then Mostly Cloudy | 12 mph NE | 22% |
| Saturday | 66°F | Cloudy | 12 to 17 mph NE | 8% |
| Saturday Night | 49°F | Mostly Cloudy | 12 to 16 mph E | 13% |
| Sunday | 62°F | Slight Chance Rain Showers | 14 mph E | 16% |
| Sunday Night | 47°F | Mostly Cloudy | 7 to 14 mph SE | 11% |
| Monday | 69°F | Mostly Sunny | 7 to 18 mph SE | 2% |
| Monday Night | 50°F | Partly Cloudy | 14 to 18 mph SE | 0% |
| Tuesday | 73°F | Mostly Sunny | 14 to 20 mph S | 1% |
| Tuesday Night | 53°F | Partly Cloudy | 10 to 20 mph S | 3% |
| Wednesday | 76°F | Mostly Sunny | 10 to 14 mph S | 6% |
| Wednesday Night | 53°F | Mostly Clear | 7 to 14 mph S | 7% |
| Thursday | 77°F | Sunny | 7 to 12 mph S | 3% |
| Thursday Night | 54°F | Mostly Clear | 12 mph SE | 4% |
| Friday | 77°F | Mostly Sunny | 10 to 18 mph SE | 3% |
Forecast source: National Weather Service (api.weather.gov) for Westby (48.870, -104.057). Updated through the day.
Growing snapshot for Westby
Last spring frost
May 18
First fall frost
Sep 21
Growing season
125 days
Hardiness zone
3b
More local growing data for Westby: nearby ZIP 59275 weather · frost dates · planting calendar · Montana frost dates
Nearby towns & communities
Climate data from the nearest NOAA station, Westby, Mt (4.8 mi from Westby). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.