Renton, Washington has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 7.4 °C (low) to 16.2 °C (high). Annual precipitation averages 1050.8 Millimeters. Renton is located in USDA Plant Hardiness Zone 9a. The growing season typically runs from the last frost around Mar. 11 - Mar. 20 through the first frost around Nov. 11 - Nov. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 2.6 °C | 8.7 °C | 141.48 mm |
| February | 2.7 °C | 10.1 °C | 104.39 mm |
| March | 4.1 °C | 12.3 °C | 115.32 mm |
| April | 6 °C | 15.2 °C | 89.41 mm |
| May | 9 °C | 19 °C | 48.26 mm |
| June | 11.5 °C | 21.4 °C | 41.66 mm |
| July | 13.5 °C | 24.9 °C | 17.27 mm |
| August | 13.6 °C | 25.2 °C | 24.38 mm |
| September | 11.4 °C | 22.1 °C | 39.88 mm |
| October | 7.9 °C | 16.1 °C | 109.22 mm |
| November | 4.6 °C | 11.3 °C | 165.1 mm |
| December | 2.4 °C | 8.3 °C | 154.43 mm |
| Annual | 7.4 °C | 16.2 °C | 1050.8 mm |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Mar. 11 - Mar. 20 |
| Average Days With Frost | 30-40 Days |
| Plant Hardiness Zone | Zone 9a : -6.7°C to -3.9°C |
| Plant Hardiness Zone - 2012 | Zone 8b : -9.4°C to -6.7°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |