Port Washington, Wisconsin has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 3.8 °C (low) to 12.7 °C (high). Annual precipitation averages 859.6 Millimeters. Port Washington is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -9.7 °C | -1.7 °C | 44.96 mm |
| February | -8.4 °C | 0.1 °C | 35.56 mm |
| March | -3.4 °C | 5.2 °C | 45.97 mm |
| April | 2 °C | 11 °C | 92.46 mm |
| May | 7.7 °C | 17.3 °C | 98.3 mm |
| June | 13.3 °C | 22.9 °C | 99.57 mm |
| July | 16.7 °C | 26.2 °C | 96.27 mm |
| August | 16.3 °C | 25.6 °C | 102.11 mm |
| September | 12.2 °C | 21.7 °C | 76.2 mm |
| October | 5.8 °C | 14.8 °C | 67.31 mm |
| November | -0.6 °C | 7.7 °C | 55.12 mm |
| December | -6.2 °C | 1.4 °C | 45.72 mm |
| Annual | 3.8 °C | 12.7 °C | 859.55 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |