DuPont, Washington has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 42.5 °F (low) to 60.6 °F (high). Annual precipitation averages 46.8 Inches. DuPont is located in USDA Plant Hardiness Zone 8b. 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 | 34.7 °F | 46.8 °F | 6.86 in. |
| February | 34.3 °F | 49.6 °F | 4.52 in. |
| March | 36.5 °F | 53.8 °F | 5.24 in. |
| April | 39.6 °F | 58.6 °F | 3.63 in. |
| May | 45.0 °F | 65.6 °F | 2.18 in. |
| June | 49.7 °F | 70.0 °F | 1.74 in. |
| July | 53.1 °F | 76.6 °F | 0.7 in. |
| August | 53.2 °F | 77.4 °F | 0.94 in. |
| September | 48.9 °F | 71.7 °F | 1.55 in. |
| October | 43.0 °F | 60.4 °F | 4.89 in. |
| November | 37.5 °F | 51.3 °F | 7.45 in. |
| December | 34.2 °F | 45.8 °F | 7.09 in. |
| Annual | 42.5 °F | 60.6 °F | 46.79 in. |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 50-75 Days |
| Plant Hardiness Zone | Zone 8b : 15°F to 20°F |
| Plant Hardiness Zone - 2012 | Zone 8b : 15°F to 20°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |