Riddle, Oregon has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 6.2 °C (low) to 19.7 °C (high). Annual precipitation averages 812 Millimeters. Riddle is located in USDA Plant Hardiness Zone 9a. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Nov. 1 - Nov. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 1.9 °C | 10.1 °C | 125.73 mm |
| February | 2.2 °C | 12.7 °C | 89.92 mm |
| March | 3.1 °C | 15.2 °C | 88.9 mm |
| April | 4.6 °C | 18.1 °C | 66.8 mm |
| May | 7.4 °C | 22.1 °C | 48.51 mm |
| June | 9.9 °C | 25.6 °C | 23.88 mm |
| July | 12.4 °C | 30.5 °C | 6.1 mm |
| August | 11.8 °C | 30.7 °C | 7.37 mm |
| September | 8.9 °C | 27.8 °C | 18.54 mm |
| October | 5.7 °C | 20.9 °C | 56.64 mm |
| November | 4.1 °C | 13.1 °C | 118.11 mm |
| December | 1.8 °C | 9.1 °C | 161.54 mm |
| Annual | 6.2 °C | 19.7 °C | 812.04 mm |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 30-40 Days |
| Plant Hardiness Zone | Zone 9a : -6.7°C to -3.9°C |
| Plant Hardiness Zone - 2012 | Zone 8b : -9.4°C to -6.7°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |