Ismay, MT Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Ismay, a town in Custer County, Montana.
Today
65°F
Showers And Thunderstorms
Showers and thunderstorms. Cloudy. High near 65, with temperatures falling to around 63 in the afternoon. East wind 7 to 10 mph. Chance of precipitation is 80%.
7-day forecast for Ismay
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 65°F | Showers And Thunderstorms | 7 to 10 mph E | 81% |
| Tonight | 52°F | Rain Showers | 12 mph E | 89% |
| Sunday | 61°F | Rain Showers | 13 mph ESE | 88% |
| Sunday Night | 49°F | Slight Chance Rain Showers then Mostly Cloudy | 5 to 12 mph ESE | 22% |
| Monday | 69°F | Partly Sunny | 5 to 13 mph SE | 4% |
| Monday Night | 50°F | Mostly Clear | 9 to 14 mph SE | 1% |
| Tuesday | 78°F | Sunny | 8 to 12 mph SSE | 0% |
| Tuesday Night | 53°F | Mostly Clear | 5 to 13 mph SSE | 1% |
| Wednesday | 81°F | Sunny | 7 mph SSE | 12% |
| Wednesday Night | 54°F | Mostly Clear | 6 mph SE | 10% |
| Thursday | 84°F | Sunny | 3 to 7 mph SSE | 2% |
| Thursday Night | 55°F | Mostly Clear | 5 to 8 mph SE | 3% |
| Friday | 83°F | Mostly Sunny | 7 to 13 mph SSE | 1% |
| Friday Night | 54°F | Partly Cloudy | 8 to 13 mph SSE | 6% |
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 Sep 19, 2026.