Longbranch, Washington has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 42.9 °F (low) to 60.9 °F (high). Annual precipitation averages 50.6 Inches. 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 | 35.2 °F | 46.9 °F | 7.58 in. |
| February | 34.8 °F | 49.7 °F | 4.84 in. |
| March | 37.0 °F | 54.2 °F | 5.65 in. |
| April | 40.0 °F | 59.5 °F | 3.78 in. |
| May | 45.5 °F | 66.5 °F | 2.37 in. |
| June | 50.1 °F | 70.7 °F | 1.65 in. |
| July | 53.6 °F | 76.8 °F | 0.63 in. |
| August | 53.6 °F | 77.3 °F | 1.11 in. |
| September | 49.4 °F | 71.6 °F | 1.79 in. |
| October | 43.4 °F | 59.8 °F | 5.04 in. |
| November | 38.0 °F | 51.5 °F | 8.36 in. |
| December | 34.7 °F | 46.0 °F | 7.78 in. |
| Annual | 42.9 °F | 60.9 °F | 50.58 in. |
| 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 : 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 |