Casco, Maine has a Subarctic With Cool Summers And Year Around Rainfall climate (Köppen classification: Dfc). Average annual temperatures range from 35 °F (low) to 55.3 °F (high). Annual precipitation averages 49.9 Inches. 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 | 9.7 °F | 29.1 °F | 3.32 in. |
| February | 10.9 °F | 32.1 °F | 3.38 in. |
| March | 20.8 °F | 40.7 °F | 3.87 in. |
| April | 32.2 °F | 53.6 °F | 4.41 in. |
| May | 43.3 °F | 65.8 °F | 3.79 in. |
| June | 53.5 °F | 74.0 °F | 4.9 in. |
| July | 59.1 °F | 79.8 °F | 4.19 in. |
| August | 57.4 °F | 78.7 °F | 3.81 in. |
| September | 49.6 °F | 71.0 °F | 3.96 in. |
| October | 38.0 °F | 57.8 °F | 5.57 in. |
| November | 28.1 °F | 45.6 °F | 4.32 in. |
| December | 17.6 °F | 34.9 °F | 4.41 in. |
| Annual | 35 °F | 55.3 °F | 49.93 in. |
| 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 : -15°F to -10°F |
| Plant Hardiness Zone - 2012 | Zone 5a : -20°F to -15°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfc - Subarctic With Cool Summers And Year Around Rainfall |