Pomeroy, Washington has a Humid Continental Climate - Dry Cool Summer climate (Köppen classification: Dsb). Average annual temperatures range from 4 °C (low) to 16.3 °C (high). Annual precipitation averages 440.7 Millimeters. Pomeroy is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -2.6 °C | 4.4 °C | 56.39 mm |
| February | -1.9 °C | 6.7 °C | 41.4 mm |
| March | 0.4 °C | 10.9 °C | 49.78 mm |
| April | 3 °C | 15.1 °C | 41.15 mm |
| May | 6.5 °C | 20 °C | 40.39 mm |
| June | 9.4 °C | 23.8 °C | 32.51 mm |
| July | 12.1 °C | 30 °C | 10.92 mm |
| August | 12.2 °C | 30.3 °C | 11.43 mm |
| September | 8.2 °C | 25 °C | 14.73 mm |
| October | 3.5 °C | 16.7 °C | 29.72 mm |
| November | -0.1 °C | 8.6 °C | 55.88 mm |
| December | -3 °C | 3.7 °C | 56.39 mm |
| Annual | 4 °C | 16.3 °C | 440.69 mm |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 7a : -17.8°C to -15°C |
| Plant Hardiness Zone - 2012 | Zone 7a : -17.8°C to -15°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dsb - Humid Continental Climate - Dry Cool Summer |