Washington, Indiana has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 44.9 °F (low) to 65.4 °F (high). Annual precipitation averages 48 Inches. Washington is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 22.7 °F | 39.0 °F | 3.5 in. |
| February | 25.2 °F | 43.6 °F | 2.86 in. |
| March | 33.8 °F | 54.2 °F | 4.04 in. |
| April | 44.0 °F | 66.6 °F | 4.98 in. |
| May | 55.0 °F | 75.9 °F | 5.55 in. |
| June | 63.5 °F | 84.1 °F | 4.77 in. |
| July | 66.3 °F | 87.0 °F | 4.15 in. |
| August | 64.2 °F | 86.0 °F | 3.19 in. |
| September | 56.5 °F | 80.7 °F | 3.78 in. |
| October | 45.2 °F | 69.1 °F | 3.5 in. |
| November | 35.0 °F | 54.8 °F | 4.04 in. |
| December | 27.1 °F | 43.4 °F | 3.64 in. |
| Annual | 44.9 °F | 65.4 °F | 48 in. |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 6b : -5°F to 0°F |
| Plant Hardiness Zone - 2012 | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |