Littleton, Maine has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from -0.7 °C (low) to 10.9 °C (high). Annual precipitation averages 1110.2 Millimeters. Littleton is located in USDA Plant Hardiness Zone 4b. The growing season typically runs from the last frost around May 21 - May 31 through the first frost around Sep.11 - Sep. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -16.4 °C | -5.1 °C | 85.85 mm |
| February | -15.5 °C | -3.3 °C | 67.82 mm |
| March | -9.2 °C | 2.1 °C | 84.07 mm |
| April | -1.7 °C | 9.6 °C | 79.76 mm |
| May | 4.6 °C | 17.7 °C | 90.68 mm |
| June | 9.9 °C | 22.9 °C | 112.27 mm |
| July | 13.1 °C | 25.5 °C | 101.35 mm |
| August | 11.9 °C | 24.8 °C | 90.42 mm |
| September | 7.7 °C | 20.3 °C | 91.19 mm |
| October | 2 °C | 12.7 °C | 106.93 mm |
| November | -3.6 °C | 4.9 °C | 96.52 mm |
| December | -10.8 °C | -1.4 °C | 103.38 mm |
| Annual | -0.7 °C | 10.9 °C | 1110.24 mm |
| Average First Frost Date | Sep.11 - Sep. 20 |
| Average Last Frost Date | May 21 - May 31 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 4b : -31.7°C to -28.9°C |
| Plant Hardiness Zone - 2012 | Zone 4a : -34.4°C to -31.7°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |