Littleton, New Hampshire has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 31.9 °F (low) to 54.4 °F (high). Annual precipitation averages 38.3 Inches. Littleton 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. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 5.7 °F | 26.9 °F | 2.2 in. |
| February | 6.5 °F | 30.3 °F | 1.88 in. |
| March | 16.8 °F | 39.5 °F | 2.22 in. |
| April | 29.8 °F | 53.0 °F | 3.01 in. |
| May | 41.6 °F | 66.5 °F | 3.58 in. |
| June | 50.8 °F | 74.9 °F | 4.02 in. |
| July | 55.8 °F | 79.7 °F | 4.26 in. |
| August | 53.8 °F | 78.2 °F | 3.97 in. |
| September | 46.3 °F | 70.8 °F | 3.41 in. |
| October | 35.4 °F | 57.0 °F | 4.02 in. |
| November | 25.8 °F | 43.9 °F | 2.66 in. |
| December | 14.5 °F | 32.4 °F | 3.06 in. |
| Annual | 31.9 °F | 54.4 °F | 38.29 in. |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 4b : -25°F to -20°F |
| Plant Hardiness Zone - 2012 | Zone 4b : -25°F to -20°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |