Bonney Lake, Washington has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 42.5 °F (low) to 59.9 °F (high). Annual precipitation averages 46.9 Inches. 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 | 34.4 °F | 46.1 °F | 6.31 in. |
| February | 34.2 °F | 48.5 °F | 4.26 in. |
| March | 36.5 °F | 52.8 °F | 4.99 in. |
| April | 39.6 °F | 57.8 °F | 4.03 in. |
| May | 45.1 °F | 64.8 °F | 2.92 in. |
| June | 49.6 °F | 69.3 °F | 2.46 in. |
| July | 53.1 °F | 76.1 °F | 1.01 in. |
| August | 53.4 °F | 76.9 °F | 1.29 in. |
| September | 49.3 °F | 70.8 °F | 1.89 in. |
| October | 42.9 °F | 59.8 °F | 4.62 in. |
| November | 37.5 °F | 50.7 °F | 6.87 in. |
| December | 33.9 °F | 45.2 °F | 6.26 in. |
| Annual | 42.5 °F | 59.9 °F | 46.91 in. |
| 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 : 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 |