Ismay, MT Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Ismay, a town in Custer County, Montana.
Today
74°F
Sunny
Sunny, with a high near 74. West northwest wind 8 to 12 mph.
7-day forecast for Ismay
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 74°F | Sunny | 8 to 12 mph WNW | 0% |
| Tonight | 49°F | Mostly Clear | 1 to 9 mph E | 1% |
| Wednesday | 84°F | Mostly Sunny | 3 to 7 mph SW | 0% |
| Wednesday Night | 55°F | Partly Cloudy | 2 to 7 mph S | 0% |
| Thursday | 92°F | Sunny | 1 to 5 mph W | 0% |
| Thursday Night | 59°F | Mostly Clear | 6 mph NE | 0% |
| Friday | 95°F | Sunny | 2 to 7 mph SE | 0% |
| Friday Night | 61°F | Partly Cloudy | 7 mph NE | 1% |
| Saturday | 95°F | Sunny | 3 to 9 mph NNE | 0% |
| Saturday Night | 62°F | Mostly Clear | 5 to 10 mph NE | 2% |
| Sunday | 94°F | Mostly Sunny | 5 to 12 mph ENE | 6% |
| Sunday Night | 62°F | Partly Cloudy then Slight Chance Rain Showers | 6 to 12 mph ENE | 22% |
| Monday | 90°F | Mostly Sunny then Slight Chance Showers And Thunderstorms | 5 to 12 mph ENE | 18% |
| Monday Night | 61°F | Slight Chance Showers And Thunderstorms then Chance Showers And Thunderstorms | 8 to 12 mph E | 38% |
Forecast source: National Weather Service (api.weather.gov) for Ismay (46.500, -104.793). Updated through the day.
Growing snapshot for Ismay
Last spring frost
May 22
First fall frost
Sep 15
Growing season
117 days
Hardiness zone
4a
More local growing data for Ismay: nearby ZIP 59336 weather · frost dates · planting calendar · Montana frost dates
Nearby towns & communities
Climate data from the nearest NOAA station, Mizpah 4 Nnw, Mt (16.7 mi from Ismay). Frost dates are 1991–2020 averages, not a forecast. Page updated Aug 4, 2026.