North Dakota frost dates by city
| City | Last frost (50%) | Safer date (10%) | First frost (50%) | Season |
|---|---|---|---|---|
| Bismarck | May 14 | May 27 | Sep 27 | 136 days |
| Fargo | May 10 | May 23 | Sep 30 | 143 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.