Granger, Wyoming has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from -2.5 °C (low) to 14.2 °C (high). Annual precipitation averages 218.5 Millimeters. Granger is located in USDA Plant Hardiness Zone 4b. The growing season typically runs from the last frost around May 21 - May 31 through the first frost around Sep.11 - Sep. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -14.2 °C | -0.1 °C | 11.18 mm |
| February | -12.4 °C | 1.9 °C | 10.41 mm |
| March | -6.7 °C | 7.8 °C | 15.75 mm |
| April | -2.7 °C | 13.1 °C | 23.37 mm |
| May | 1.9 °C | 18.6 °C | 36.83 mm |
| June | 6.1 °C | 24.9 °C | 23.62 mm |
| July | 9.6 °C | 29.8 °C | 13.46 mm |
| August | 8.4 °C | 28.8 °C | 17.02 mm |
| September | 3.6 °C | 23.4 °C | 23.37 mm |
| October | -2.3 °C | 15.3 °C | 21.59 mm |
| November | -7.8 °C | 6.8 °C | 11.94 mm |
| December | -13.3 °C | 0.6 °C | 9.91 mm |
| Annual | -2.5 °C | 14.2 °C | 218.45 mm |
| Average First Frost Date | Sep.11 - Sep. 20 |
| Average Last Frost Date | May 21 - May 31 |
| 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 | Severe Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |