Deep River, Washington has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 5.6 °C (low) to 15.8 °C (high). Annual precipitation averages 2536.2 Millimeters. Deep River 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 Nov. 1 - Nov. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 2.1 °C | 9.1 °C | 406.15 mm |
| February | 1.6 °C | 10.6 °C | 249.68 mm |
| March | 2.6 °C | 12.3 °C | 282.45 mm |
| April | 3.9 °C | 14.9 °C | 196.09 mm |
| May | 6.7 °C | 17.7 °C | 106.93 mm |
| June | 8.9 °C | 19.7 °C | 86.11 mm |
| July | 10.9 °C | 22.3 °C | 27.43 mm |
| August | 10.9 °C | 23.3 °C | 40.64 mm |
| September | 9.1 °C | 22.2 °C | 96.01 mm |
| October | 5.8 °C | 17.2 °C | 241.55 mm |
| November | 3.3 °C | 11.7 °C | 395.48 mm |
| December | 1.7 °C | 8.7 °C | 407.67 mm |
| Annual | 5.6 °C | 15.8 °C | 2536.19 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 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 |