Washington, Connecticut has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 38.7 °F (low) to 59.3 °F (high). Annual precipitation averages 49.8 Inches. Washington is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 16.5 °F | 35.2 °F | 3.4 in. |
| February | 18.3 °F | 38.1 °F | 2.87 in. |
| March | 25.4 °F | 45.8 °F | 4.07 in. |
| April | 35.7 °F | 58.6 °F | 3.81 in. |
| May | 46.1 °F | 69.2 °F | 4.03 in. |
| June | 55.2 °F | 77.2 °F | 4.5 in. |
| July | 60.6 °F | 81.9 °F | 4.66 in. |
| August | 59.4 °F | 80.3 °F | 4.8 in. |
| September | 52.1 °F | 72.9 °F | 4.51 in. |
| October | 40.6 °F | 61.6 °F | 5.06 in. |
| November | 31.2 °F | 50.8 °F | 3.79 in. |
| December | 22.8 °F | 39.7 °F | 4.32 in. |
| Annual | 38.7 °F | 59.3 °F | 49.82 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6a : -10°F to -5°F |
| Plant Hardiness Zone - 2012 | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |