Cathcart, Washington has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 43.3 °F (low) to 59.7 °F (high). Annual precipitation averages 46.1 Inches. Cathcart 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 Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 34.9 °F | 46.5 °F | 5.99 in. |
| February | 34.9 °F | 49.2 °F | 4.33 in. |
| March | 37.4 °F | 53.2 °F | 4.84 in. |
| April | 40.9 °F | 57.8 °F | 3.9 in. |
| May | 46.2 °F | 64.5 °F | 2.8 in. |
| June | 50.4 °F | 68.7 °F | 2.38 in. |
| July | 53.8 °F | 74.6 °F | 1.03 in. |
| August | 53.9 °F | 75.5 °F | 1.11 in. |
| September | 50.0 °F | 70.1 °F | 2.27 in. |
| October | 43.8 °F | 59.4 °F | 4.41 in. |
| November | 38.3 °F | 50.9 °F | 6.8 in. |
| December | 34.6 °F | 45.5 °F | 6.27 in. |
| Annual | 43.3 °F | 59.7 °F | 46.13 in. |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 50-75 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 | Normal |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |