Boulder, MT Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Boulder, a city in Jefferson County, Montana.
Today
48°F
Mostly Sunny
Mostly sunny. High near 48, with temperatures falling to around 42 in the afternoon. Southwest wind 1 to 6 mph.
7-day forecast for Boulder
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 48°F | Mostly Sunny | 1 to 6 mph SW | 0% |
| Tonight | 28°F | Mostly Cloudy | 3 mph W | 0% |
| Wednesday | 49°F | Mostly Sunny | 0 to 3 mph N | 0% |
| Wednesday Night | 27°F | Mostly Clear | 0 to 5 mph WSW | 0% |
| Thursday | 48°F | Mostly Sunny | 3 to 7 mph SW | 6% |
| Thursday Night | 28°F | Partly Cloudy | 3 to 7 mph WSW | 6% |
| Friday | 48°F | Mostly Sunny | 6 to 12 mph SW | 6% |
| Friday Night | 30°F | Partly Cloudy | 7 to 17 mph WSW | 6% |
| Saturday | 51°F | Mostly Sunny | 5 to 8 mph SW | 0% |
| Saturday Night | 33°F | Partly Cloudy | 5 to 10 mph SSW | 0% |
| Sunday | 56°F | Mostly Sunny | 7 to 10 mph SSW | 1% |
| Sunday Night | 33°F | Mostly Cloudy | 5 to 9 mph SW | 1% |
| Monday | 53°F | Partly Sunny | 3 to 7 mph SW | 2% |
| Monday Night | 35°F | Mostly Cloudy | 3 to 7 mph SW | 2% |
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 Nov 3, 2026.