Longbranch, Washington has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 6.1 °C (low) to 16 °C (high). Annual precipitation averages 1284.7 Millimeters. Longbranch 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 | 1.8 °C | 8.3 °C | 192.53 mm |
| February | 1.6 °C | 9.8 °C | 122.94 mm |
| March | 2.8 °C | 12.3 °C | 143.51 mm |
| April | 4.4 °C | 15.3 °C | 96.01 mm |
| May | 7.5 °C | 19.2 °C | 60.2 mm |
| June | 10.1 °C | 21.5 °C | 41.91 mm |
| July | 12 °C | 24.9 °C | 16 mm |
| August | 12 °C | 25.2 °C | 28.19 mm |
| September | 9.7 °C | 22 °C | 45.47 mm |
| October | 6.3 °C | 15.4 °C | 128.02 mm |
| November | 3.3 °C | 10.8 °C | 212.34 mm |
| December | 1.5 °C | 7.8 °C | 197.61 mm |
| Annual | 6.1 °C | 16 °C | 1284.73 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 50-75 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 |