Portland, Oregon has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 45.3 °F (low) to 63.2 °F (high). Annual precipitation averages 43.1 Inches. Portland is located in USDA Plant Hardiness Zone 9a. The growing season typically runs from the last frost around Feb. 21 - Feb. 29 through the first frost around Dec. 1 - Dec. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 36.3 °F | 47.0 °F | 6.43 in. |
| February | 36.9 °F | 50.8 °F | 4.52 in. |
| March | 39.3 °F | 55.9 °F | 4.64 in. |
| April | 42.7 °F | 61.1 °F | 3.52 in. |
| May | 48.1 °F | 68.3 °F | 2.42 in. |
| June | 52.4 °F | 73.1 °F | 1.64 in. |
| July | 56.4 °F | 80.7 °F | 0.42 in. |
| August | 56.5 °F | 81.6 °F | 0.54 in. |
| September | 52.2 °F | 75.8 °F | 1.49 in. |
| October | 45.9 °F | 64.1 °F | 3.68 in. |
| November | 40.4 °F | 53.1 °F | 6.39 in. |
| December | 36.2 °F | 46.5 °F | 7.4 in. |
| Annual | 45.3 °F | 63.2 °F | 43.09 in. |
| Average First Frost Date | Dec. 1 - Dec. 10 |
| Average Last Frost Date | Feb. 21 - Feb. 29 |
| Average Days With Frost | 10-20 Days |
| Plant Hardiness Zone | Zone 9a : 20°F to 25°F |
| Plant Hardiness Zone - 2012 | Zone 9a : 20°F to 25°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |