Richmond, Maine has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 2.2 °C (low) to 13 °C (high). Annual precipitation averages 1239.3 Millimeters. Richmond is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -11.6 °C | -0.9 °C | 92.2 mm |
| February | -10.6 °C | 0.8 °C | 84.33 mm |
| March | -5.2 °C | 5.1 °C | 101.09 mm |
| April | 0.6 °C | 11.7 °C | 110.49 mm |
| May | 6.4 °C | 17.9 °C | 92.46 mm |
| June | 11.6 °C | 22.8 °C | 115.32 mm |
| July | 14.9 °C | 26.1 °C | 89.66 mm |
| August | 14.2 °C | 25.6 °C | 86.87 mm |
| September | 10.2 °C | 21.6 °C | 100.33 mm |
| October | 4.2 °C | 14.7 °C | 137.67 mm |
| November | -1.2 °C | 8.3 °C | 113.79 mm |
| December | -7.1 °C | 2.5 °C | 115.06 mm |
| Annual | 2.2 °C | 13 °C | 1239.27 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5b : -26.1°C to -23.3°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |