Roundup, MT Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Roundup, a city in Musselshell County, Montana.
This Afternoon
79°F
Mostly Sunny
Mostly sunny. High near 79, with temperatures falling to around 77 in the afternoon. North northeast wind 8 to 12 mph.
7-day forecast for Roundup
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| This Afternoon | 79°F | Mostly Sunny | 8 to 12 mph NNE | 11% |
| Tonight | 53°F | Chance Showers And Thunderstorms | 6 to 10 mph NNE | 92% |
| Saturday | 60°F | Showers And Thunderstorms | 14 mph NNE | 95% |
| Saturday Night | 50°F | Showers And Thunderstorms | 9 to 13 mph NNE | 88% |
| Sunday | 63°F | Rain Showers | 8 mph NNE | 78% |
| Sunday Night | 48°F | Mostly Cloudy | 0 to 7 mph E | 10% |
| Monday | 74°F | Mostly Sunny | 2 to 7 mph SSW | 0% |
| Monday Night | 49°F | Mostly Clear | 1 to 7 mph S | 0% |
| Tuesday | 80°F | Mostly Sunny | 5 mph SW | 0% |
| Tuesday Night | 51°F | Partly Cloudy | 0 to 3 mph SSE | 3% |
| Wednesday | 80°F | Sunny | 6 mph WSW | 3% |
| Wednesday Night | 51°F | Mostly Clear | 0 to 3 mph SSW | 3% |
| Thursday | 80°F | Sunny | 7 mph SSW | 1% |
| Thursday Night | 51°F | Mostly Clear | 1 to 5 mph SSE | 3% |
Forecast source: National Weather Service (api.weather.gov) for Roundup (46.448, -108.540). Updated through the day.
Growing snapshot for Roundup
Last spring frost
May 20
First fall frost
Sep 21
Growing season
124 days
Hardiness zone
4b
More local growing data for Roundup: nearby ZIP 59072 weather · frost dates · planting calendar · Montana frost dates
Nearby towns & communities
Climate data from the nearest NOAA station, Roundup, Mt (6.2 mi from Roundup). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 18, 2026.