Boulder, MT Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Boulder, a city in Jefferson County, Montana.
Tonight
50°F
Showers And Thunderstorms
Showers and thunderstorms. Cloudy, with a low around 50. North wind around 6 mph. Chance of precipitation is 100%. New rainfall amounts between three quarters and one inch possible.
7-day forecast for Boulder
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 50°F | Showers And Thunderstorms | 6 mph N | 97% |
| Saturday | 55°F | Showers And Thunderstorms | 7 mph NNE | 100% |
| Saturday Night | 45°F | Chance Light Rain then Mostly Cloudy | 0 to 5 mph NW | 29% |
| Sunday | 68°F | Mostly Sunny | 2 to 6 mph S | 2% |
| Sunday Night | 45°F | Mostly Clear | 2 to 6 mph SSW | 0% |
| Monday | 73°F | Sunny | 2 to 6 mph SW | 0% |
| Monday Night | 47°F | Mostly Clear | 2 to 6 mph W | 0% |
| Tuesday | 73°F | Sunny | 2 to 7 mph SW | 1% |
| Tuesday Night | 48°F | Partly Cloudy | 5 mph W | 4% |
| Wednesday | 74°F | Sunny | 3 to 8 mph SW | 2% |
| Wednesday Night | 48°F | Mostly Clear | 2 to 6 mph WSW | 3% |
| Thursday | 75°F | Sunny | 5 to 8 mph S | 2% |
| Thursday Night | 49°F | Mostly Clear | 6 mph S | 3% |
| Friday | 75°F | Mostly Sunny | 6 to 9 mph SSW | 1% |
Forecast source: National Weather Service (api.weather.gov) for Boulder (46.236, -112.120). Updated through the day.
Growing snapshot for Boulder
Last spring frost
Jun 7
First fall frost
Sep 8
Growing season
90 days
Hardiness zone
5a
More local growing data for Boulder: nearby ZIP 59632 weather · frost dates · planting calendar · Montana frost dates
Nearby towns & communities
Climate data from the nearest NOAA station, Boulder, Mt (6.8 mi from Boulder). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.