Houlton, Maine has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 31 °F (low) to 52 °F (high). Annual precipitation averages 41.7 Inches. Houlton 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 | 2.8 °F | 23.3 °F | 3.43 in. |
| February | 4.3 °F | 26.7 °F | 2.66 in. |
| March | 15.9 °F | 36.2 °F | 3.07 in. |
| April | 29.2 °F | 49.5 °F | 3.2 in. |
| May | 40.6 °F | 64.1 °F | 3.32 in. |
| June | 49.9 °F | 73.3 °F | 4.1 in. |
| July | 55.6 °F | 78.2 °F | 3.61 in. |
| August | 53.7 °F | 77.2 °F | 3.38 in. |
| September | 46.0 °F | 69.0 °F | 3.24 in. |
| October | 35.6 °F | 55.3 °F | 3.91 in. |
| November | 26.0 °F | 41.6 °F | 3.7 in. |
| December | 12.8 °F | 29.9 °F | 4.04 in. |
| Annual | 31 °F | 52 °F | 41.66 in. |
| 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 : -25°F to -20°F |
| Plant Hardiness Zone - 2012 | Zone 4a : -30°F to -25°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |