Alsea, Oregon has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 41.6 °F (low) to 61.8 °F (high). Annual precipitation averages 69.4 Inches. Alsea is located in USDA Plant Hardiness Zone 8b. The growing season typically runs from the last frost around Mar. 21 - Mar. 31 through the first frost around Nov. 21 - Nov. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 34.7 °F | 46.4 °F | 10.75 in. |
| February | 34.7 °F | 50.0 °F | 8.55 in. |
| March | 36.5 °F | 54.3 °F | 8.69 in. |
| April | 38.8 °F | 60.0 °F | 5.17 in. |
| May | 43.5 °F | 66.3 °F | 3.34 in. |
| June | 47.2 °F | 71.2 °F | 1.91 in. |
| July | 50.3 °F | 79.4 °F | 0.42 in. |
| August | 50.6 °F | 79.6 °F | 0.5 in. |
| September | 47.7 °F | 74.6 °F | 2.16 in. |
| October | 42.6 °F | 62.3 °F | 5.11 in. |
| November | 37.9 °F | 51.7 °F | 10.49 in. |
| December | 34.4 °F | 45.3 °F | 12.27 in. |
| Annual | 41.6 °F | 61.8 °F | 69.36 in. |
| Average First Frost Date | Nov. 21 - Nov. 30 |
| Average Last Frost Date | Mar. 21 - Mar. 31 |
| Average Days With Frost | 40-50 Days |
| Plant Hardiness Zone | Zone 8b : 15°F to 20°F |
| Plant Hardiness Zone - 2012 | Zone 8b : 15°F to 20°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |