Williams, Oregon has a Hot-Summer Mediterranean Climate climate (Köppen classification: Csa). Average annual temperatures range from 4.6 °C (low) to 20.1 °C (high). Annual precipitation averages 802.9 Millimeters. Williams is located in USDA Plant Hardiness Zone 8b. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -0.3 °C | 9.3 °C | 143 mm |
| February | 0.2 °C | 12.4 °C | 97.28 mm |
| March | 1.3 °C | 15.2 °C | 91.19 mm |
| April | 3.1 °C | 18.2 °C | 59.69 mm |
| May | 6.1 °C | 23.2 °C | 36.83 mm |
| June | 8.8 °C | 27.3 °C | 16.76 mm |
| July | 11.5 °C | 32.7 °C | 6.35 mm |
| August | 10.8 °C | 32.7 °C | 5.84 mm |
| September | 7.8 °C | 28.2 °C | 13.72 mm |
| October | 3.8 °C | 20.7 °C | 50.8 mm |
| November | 1.7 °C | 12.7 °C | 112.78 mm |
| December | -0.2 °C | 8.3 °C | 168.66 mm |
| Annual | 4.6 °C | 20.1 °C | 802.9 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 100-125 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 | Severe Drought |
| Köppen Climate Classification | Csa - Hot-Summer Mediterranean Climate |