Blaine, Washington has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 43.7 °F (low) to 57.7 °F (high). Annual precipitation averages 42.8 Inches. Blaine 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. 1 - Nov. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 34.9 °F | 44.7 °F | 6.26 in. |
| February | 35.3 °F | 47.4 °F | 3.54 in. |
| March | 37.7 °F | 51.3 °F | 4.34 in. |
| April | 41.5 °F | 56.7 °F | 3.19 in. |
| May | 46.8 °F | 62.7 °F | 2.57 in. |
| June | 51.5 °F | 67.0 °F | 1.96 in. |
| July | 54.7 °F | 71.8 °F | 1.24 in. |
| August | 54.5 °F | 71.9 °F | 1.16 in. |
| September | 50.2 °F | 66.9 °F | 2.2 in. |
| October | 44.2 °F | 57.7 °F | 4.38 in. |
| November | 38.7 °F | 49.9 °F | 6.16 in. |
| December | 34.7 °F | 44.3 °F | 5.76 in. |
| Annual | 43.7 °F | 57.7 °F | 42.76 in. |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| 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 8a : 10°F to 15°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |