Maryhill, Washington has a Humid Continental Climate - Dry Cool Summer climate (Köppen classification: Dsb). Average annual temperatures range from 6.9 °C (low) to 18.4 °C (high). Annual precipitation averages 273 Millimeters. Maryhill is located in USDA Plant Hardiness Zone 8a. 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 | 0.1 °C | 6.1 °C | 48.26 mm |
| February | 0.6 °C | 9.1 °C | 32.26 mm |
| March | 2.9 °C | 13.8 °C | 25.15 mm |
| April | 5.6 °C | 17.5 °C | 15.49 mm |
| May | 9.3 °C | 22.2 °C | 16 mm |
| June | 12.4 °C | 25.8 °C | 8.38 mm |
| July | 15.7 °C | 31.3 °C | 3.81 mm |
| August | 15.7 °C | 31.7 °C | 4.06 mm |
| September | 11.6 °C | 26.9 °C | 6.86 mm |
| October | 6.6 °C | 19.1 °C | 19.3 mm |
| November | 2.7 °C | 11 °C | 38.86 mm |
| December | 0.1 °C | 5.9 °C | 54.61 mm |
| Annual | 6.9 °C | 18.4 °C | 273.04 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 8a : -12.2°C to -9.4°C |
| Plant Hardiness Zone - 2012 | Zone 7b : -15°C to -12.2°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dsb - Humid Continental Climate - Dry Cool Summer |