Ranchester, Wyoming has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from -0.5 °C (low) to 15 °C (high). Annual precipitation averages 387.6 Millimeters. Ranchester is located in USDA Plant Hardiness Zone 4b. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Sep.11 - Sep. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -11.7 °C | 2.2 °C | 12.95 mm |
| February | -10.5 °C | 3.5 °C | 15.49 mm |
| March | -5.8 °C | 9.2 °C | 30.48 mm |
| April | -1.1 °C | 13.3 °C | 51.05 mm |
| May | 4 °C | 18.4 °C | 83.57 mm |
| June | 8.8 °C | 24.3 °C | 42.93 mm |
| July | 12.1 °C | 30.2 °C | 28.96 mm |
| August | 10.7 °C | 29.6 °C | 20.32 mm |
| September | 5.8 °C | 23.6 °C | 38.1 mm |
| October | -0.6 °C | 15.3 °C | 32.26 mm |
| November | -6.7 °C | 8.1 °C | 18.8 mm |
| December | -11.3 °C | 2.4 °C | 12.7 mm |
| Annual | -0.5 °C | 15 °C | 387.61 mm |
| Average First Frost Date | Sep.11 - Sep. 20 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | Over 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 | Dfb - Humid Continental Mild Summer, Wet All Year |