Chico, Washington has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 6.8 °C (low) to 16.1 °C (high). Annual precipitation averages 1254.5 Millimeters. Chico is located in USDA Plant Hardiness Zone 9a. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Nov. 1 - Nov. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 2.3 °C | 8.5 °C | 196.09 mm |
| February | 2.2 °C | 9.9 °C | 119.38 mm |
| March | 3.4 °C | 12.2 °C | 133.86 mm |
| April | 5.2 °C | 15.2 °C | 85.85 mm |
| May | 8.2 °C | 19.1 °C | 53.59 mm |
| June | 10.6 °C | 21.3 °C | 40.39 mm |
| July | 12.6 °C | 24.8 °C | 21.08 mm |
| August | 12.7 °C | 25.2 °C | 26.42 mm |
| September | 10.6 °C | 22.2 °C | 46.99 mm |
| October | 7.3 °C | 16.1 °C | 118.87 mm |
| November | 4.1 °C | 10.9 °C | 197.87 mm |
| December | 2.2 °C | 8 °C | 214.12 mm |
| Annual | 6.8 °C | 16.1 °C | 1254.51 mm |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 40-50 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 | Moderate Drought |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |