Northport, Washington has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 37.4 °F (low) to 59.6 °F (high). Annual precipitation averages 20.5 Inches. Northport is located in USDA Plant Hardiness Zone 6b. 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 | 24.4 °F | 33.5 °F | 2.24 in. |
| February | 25.1 °F | 39.8 °F | 1.43 in. |
| March | 29.8 °F | 50.2 °F | 1.73 in. |
| April | 35.0 °F | 60.9 °F | 1.61 in. |
| May | 43.2 °F | 70.8 °F | 2.07 in. |
| June | 48.8 °F | 76.3 °F | 2.45 in. |
| July | 53.3 °F | 86.3 °F | 1.06 in. |
| August | 52.5 °F | 87.0 °F | 0.66 in. |
| September | 45.7 °F | 75.9 °F | 0.97 in. |
| October | 36.4 °F | 58.6 °F | 1.54 in. |
| November | 30.5 °F | 42.5 °F | 2.37 in. |
| December | 24.5 °F | 33.4 °F | 2.36 in. |
| Annual | 37.4 °F | 59.6 °F | 20.49 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 6b : -5°F to 0°F |
| Plant Hardiness Zone - 2012 | Zone 6b : -5°F to 0°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |