Evanston, Wyoming has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from -2.5 °C (low) to 13 °C (high). Annual precipitation averages 310.2 Millimeters. Evanston is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around May 21 - May 31 through the first frost around Sep.1 - Sep. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -11.9 °C | 0.3 °C | 18.54 mm |
| February | -11.3 °C | 1.6 °C | 16.26 mm |
| March | -6.8 °C | 6.6 °C | 18.29 mm |
| April | -3.4 °C | 10.8 °C | 29.46 mm |
| May | 0.8 °C | 16.3 °C | 42.93 mm |
| June | 4.4 °C | 22.4 °C | 30.99 mm |
| July | 8.7 °C | 27.9 °C | 18.29 mm |
| August | 8.1 °C | 26.9 °C | 26.42 mm |
| September | 3.6 °C | 21.8 °C | 32.26 mm |
| October | -2.2 °C | 14.3 °C | 30.99 mm |
| November | -7.4 °C | 6.2 °C | 24.64 mm |
| December | -12.2 °C | 0.4 °C | 21.08 mm |
| Annual | -2.5 °C | 13 °C | 310.15 mm |
| Average First Frost Date | Sep.1 - Sep. 10 |
| Average Last Frost Date | May 21 - May 31 |
| 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 | Severe Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |