Alger, Washington has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 42.5 °F (low) to 59.4 °F (high). Annual precipitation averages 50.9 Inches. Alger is located in USDA Plant Hardiness Zone 8b. 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 | 33.9 °F | 44.7 °F | 6.47 in. |
| February | 34.4 °F | 47.3 °F | 3.37 in. |
| March | 36.7 °F | 52.0 °F | 5.92 in. |
| April | 40.4 °F | 58.5 °F | 4.18 in. |
| May | 45.4 °F | 65.0 °F | 3.19 in. |
| June | 50.0 °F | 69.6 °F | 2.44 in. |
| July | 53.0 °F | 75.4 °F | 1.4 in. |
| August | 53.0 °F | 76.6 °F | 1.51 in. |
| September | 48.9 °F | 70.8 °F | 2.12 in. |
| October | 43.1 °F | 59.7 °F | 5.77 in. |
| November | 37.8 °F | 49.6 °F | 8.54 in. |
| December | 33.8 °F | 44.0 °F | 5.96 in. |
| Annual | 42.5 °F | 59.4 °F | 50.87 in. |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 40-50 Days |
| Plant Hardiness Zone | Zone 8b : 15°F to 20°F |
| Plant Hardiness Zone - 2012 | Zone 8a : 10°F to 15°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |