Casco, Maine has a Subarctic With Cool Summers And Year Around Rainfall climate (Köppen classification: Dfc). Average annual temperatures range from 1.7 °C (low) to 12.9 °C (high). Annual precipitation averages 1268.2 Millimeters. Casco is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -12.4 °C | -1.6 °C | 84.33 mm |
| February | -11.7 °C | 0.1 °C | 85.85 mm |
| March | -6.2 °C | 4.8 °C | 98.3 mm |
| April | 0.1 °C | 12 °C | 112.01 mm |
| May | 6.3 °C | 18.8 °C | 96.27 mm |
| June | 11.9 °C | 23.3 °C | 124.46 mm |
| July | 15.1 °C | 26.6 °C | 106.43 mm |
| August | 14.1 °C | 25.9 °C | 96.77 mm |
| September | 9.8 °C | 21.7 °C | 100.58 mm |
| October | 3.3 °C | 14.3 °C | 141.48 mm |
| November | -2.2 °C | 7.6 °C | 109.73 mm |
| December | -8 °C | 1.6 °C | 112.01 mm |
| Annual | 1.7 °C | 12.9 °C | 1268.22 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| 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 | Normal |
| Köppen Climate Classification | Dfc - Subarctic With Cool Summers And Year Around Rainfall |