Bethel, Washington has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 43.1 °F (low) to 60 °F (high). Annual precipitation averages 51.6 Inches. Bethel is located in USDA Plant Hardiness Zone 8b. The growing season typically runs from the last frost around Mar. 21 - Mar. 31 through the first frost around Nov. 11 - Nov. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 35.2 °F | 46.3 °F | 8.01 in. |
| February | 34.8 °F | 48.8 °F | 4.8 in. |
| March | 37.2 °F | 53.0 °F | 5.84 in. |
| April | 40.3 °F | 58.4 °F | 3.81 in. |
| May | 45.7 °F | 65.4 °F | 2.07 in. |
| June | 50.1 °F | 69.4 °F | 1.61 in. |
| July | 53.6 °F | 75.6 °F | 0.8 in. |
| August | 53.8 °F | 76.3 °F | 1.07 in. |
| September | 50.0 °F | 70.8 °F | 1.86 in. |
| October | 44.0 °F | 59.7 °F | 4.95 in. |
| November | 38.2 °F | 50.7 °F | 8.22 in. |
| December | 34.8 °F | 45.4 °F | 8.51 in. |
| Annual | 43.1 °F | 60 °F | 51.55 in. |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Mar. 21 - Mar. 31 |
| 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 | Abnormally Dry |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |