Bonney Lake, Washington has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 5.8 °C (low) to 15.5 °C (high). Annual precipitation averages 1191.5 Millimeters. Bonney Lake is located in USDA Plant Hardiness Zone 8b. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 1.3 °C | 7.8 °C | 160.27 mm |
| February | 1.2 °C | 9.2 °C | 108.2 mm |
| March | 2.5 °C | 11.6 °C | 126.75 mm |
| April | 4.2 °C | 14.3 °C | 102.36 mm |
| May | 7.3 °C | 18.2 °C | 74.17 mm |
| June | 9.8 °C | 20.7 °C | 62.48 mm |
| July | 11.7 °C | 24.5 °C | 25.65 mm |
| August | 11.9 °C | 24.9 °C | 32.77 mm |
| September | 9.6 °C | 21.6 °C | 48.01 mm |
| October | 6.1 °C | 15.4 °C | 117.35 mm |
| November | 3.1 °C | 10.4 °C | 174.5 mm |
| December | 1.1 °C | 7.3 °C | 159 mm |
| Annual | 5.8 °C | 15.5 °C | 1191.51 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 40-50 Days |
| Plant Hardiness Zone | Zone 8b : -9.4°C to -6.7°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 |