Montana frost dates by city
| City | Last frost (50%) | Safer date (10%) | First frost (50%) | Season |
|---|---|---|---|---|
| Billings | May 4 | May 18 | Oct 7 | 156 days |
| Missoula | May 16 | Jun 1 | Sep 26 | 130 days |
Each city uses its nearest major NOAA weather station, usually the airport. Valleys, hilltops and rural spots can differ from it by one to three weeks. How to read these dates.