Geyser, Montana has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from -0.6 °C (low) to 13.6 °C (high). Annual precipitation averages 417.6 Millimeters. Geyser 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.11 - Sep. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -9.8 °C | 2.4 °C | 13.21 mm |
| February | -9.3 °C | 3.1 °C | 12.45 mm |
| March | -5.9 °C | 7.4 °C | 16.76 mm |
| April | -1.9 °C | 12 °C | 43.18 mm |
| May | 2.7 °C | 17 °C | 67.06 mm |
| June | 7 °C | 21.7 °C | 77.47 mm |
| July | 10.1 °C | 27.7 °C | 43.94 mm |
| August | 9.3 °C | 27.6 °C | 38.86 mm |
| September | 5.1 °C | 21.7 °C | 40.39 mm |
| October | -0.1 °C | 13.7 °C | 31.5 mm |
| November | -5.4 °C | 6.8 °C | 17.02 mm |
| December | -9.2 °C | 2.5 °C | 15.75 mm |
| Annual | -0.6 °C | 13.6 °C | 417.59 mm |
| Average First Frost Date | Sep.11 - Sep. 20 |
| 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 4b : -31.7°C to -28.9°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |