Waterboro, Maine has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 1.7 °C (low) to 13.2 °C (high). Annual precipitation averages 1275.8 Millimeters. Waterboro is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -11.6 °C | -1.5 °C | 88.9 mm |
| February | -11.4 °C | 0.2 °C | 90.42 mm |
| March | -6.3 °C | 4.8 °C | 109.22 mm |
| April | 0.2 °C | 12.4 °C | 117.09 mm |
| May | 6.3 °C | 19.3 °C | 94.23 mm |
| June | 11.7 °C | 24.2 °C | 115.06 mm |
| July | 14.7 °C | 27.1 °C | 104.39 mm |
| August | 13.8 °C | 26.3 °C | 95.5 mm |
| September | 9.6 °C | 21.8 °C | 98.04 mm |
| October | 3.6 °C | 14.1 °C | 138.18 mm |
| November | -1.9 °C | 7.5 °C | 108.71 mm |
| December | -7.8 °C | 1.6 °C | 116.08 mm |
| Annual | 1.7 °C | 13.2 °C | 1275.82 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5b : -26.1°C to -23.3°C |
| Plant Hardiness Zone - 2012 | Zone 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |