Oregon City, Oregon has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 7.3 °C (low) to 17.6 °C (high). Annual precipitation averages 1124.5 Millimeters. Oregon City is located in USDA Plant Hardiness Zone 9a. The growing season typically runs from the last frost around Mar. 11 - Mar. 20 through the first frost around Nov. 11 - Nov. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 2.4 °C | 8.5 °C | 162.81 mm |
| February | 2.7 °C | 10.7 °C | 114.55 mm |
| March | 3.9 °C | 13.4 °C | 123.44 mm |
| April | 5.8 °C | 16.4 °C | 97.28 mm |
| May | 8.8 °C | 20.4 °C | 60.71 mm |
| June | 11.2 °C | 23.3 °C | 41.91 mm |
| July | 13.4 °C | 27.7 °C | 10.67 mm |
| August | 13.4 °C | 28 °C | 15.24 mm |
| September | 11.1 °C | 24.7 °C | 38.1 mm |
| October | 7.6 °C | 18 °C | 99.31 mm |
| November | 4.6 °C | 11.7 °C | 169.93 mm |
| December | 2.2 °C | 8.1 °C | 190.5 mm |
| Annual | 7.3 °C | 17.6 °C | 1124.45 mm |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Mar. 11 - Mar. 20 |
| Average Days With Frost | 20-30 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 | Abnormally Dry |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |