Ulm, Montana has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 0.9 °C (low) to 14.7 °C (high). Annual precipitation averages 367.5 Millimeters. Ulm is located in USDA Plant Hardiness Zone 4b. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -8.9 °C | 2.6 °C | 12.95 mm |
| February | -8.4 °C | 3.8 °C | 12.7 mm |
| March | -4.8 °C | 8.5 °C | 15.49 mm |
| April | -0.2 °C | 13.4 °C | 42.67 mm |
| May | 4.6 °C | 18.6 °C | 58.42 mm |
| June | 8.8 °C | 23.2 °C | 73.91 mm |
| July | 11.7 °C | 29.4 °C | 28.96 mm |
| August | 10.9 °C | 28.9 °C | 31.75 mm |
| September | 6.6 °C | 22.8 °C | 33.78 mm |
| October | 1.4 °C | 14.9 °C | 26.92 mm |
| November | -3.6 °C | 7.7 °C | 16.76 mm |
| December | -7.9 °C | 2.9 °C | 13.21 mm |
| Annual | 0.9 °C | 14.7 °C | 367.52 mm |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 4b : -31.7°C to -28.9°C |
| Plant Hardiness Zone - 2012 | Zone 4a : -34.4°C to -31.7°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |