Glenrock, Wyoming has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 0.8 °C (low) to 15.9 °C (high). Annual precipitation averages 339.6 Millimeters. Glenrock is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Sep.11 - Sep. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -8.9 °C | 3.3 °C | 10.16 mm |
| February | -8.3 °C | 4.3 °C | 17.02 mm |
| March | -4.3 °C | 9.9 °C | 22.86 mm |
| April | -0.8 °C | 13.7 °C | 48.51 mm |
| May | 4.3 °C | 19.1 °C | 60.96 mm |
| June | 9.1 °C | 26 °C | 46.74 mm |
| July | 13.1 °C | 31.4 °C | 25.15 mm |
| August | 11.9 °C | 30.3 °C | 25.65 mm |
| September | 6.4 °C | 24.5 °C | 26.16 mm |
| October | 0.2 °C | 15.9 °C | 30.48 mm |
| November | -5 °C | 8.5 °C | 15.24 mm |
| December | -8.7 °C | 3.3 °C | 10.67 mm |
| Annual | 0.8 °C | 15.9 °C | 339.6 mm |
| Average First Frost Date | Sep.11 - Sep. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 5a : -28.9°C to -26.1°C |
| Plant Hardiness Zone - 2012 | Zone 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Extreme Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |