Sleepy Hollow, Wyoming has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 0.6 °C (low) to 14.7 °C (high). Annual precipitation averages 445 Millimeters. Sleepy Hollow is located in USDA Plant Hardiness Zone 5a. 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 | -10.2 °C | 1.8 °C | 14.73 mm |
| February | -9.3 °C | 2.7 °C | 19.3 mm |
| March | -4.9 °C | 8.5 °C | 28.19 mm |
| April | -0.9 °C | 12.9 °C | 52.07 mm |
| May | 4.2 °C | 18 °C | 83.06 mm |
| June | 9.4 °C | 24.6 °C | 66.04 mm |
| July | 13.2 °C | 29.9 °C | 44.45 mm |
| August | 12.5 °C | 29.6 °C | 32.51 mm |
| September | 7.1 °C | 23.8 °C | 32 mm |
| October | 0.6 °C | 15.2 °C | 39.12 mm |
| November | -5.3 °C | 7.6 °C | 16.26 mm |
| December | -9.7 °C | 2.1 °C | 17.27 mm |
| Annual | 0.6 °C | 14.7 °C | 445 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 5a : -28.9°C to -26.1°C |
| Plant Hardiness Zone - 2012 | Zone 4b : -31.7°C to -28.9°C |
| Current Drought Conditions | Extreme Drought |
| Köppen Climate Classification | BSk - Cold Semi-Arid Climate |