Altoona, Washington has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 6.9 °C (low) to 15.2 °C (high). Annual precipitation averages 2534.4 Millimeters. Altoona is located in USDA Plant Hardiness Zone 9a. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 3.1 °C | 8.8 °C | 402.08 mm |
| February | 3.1 °C | 10.4 °C | 250.19 mm |
| March | 3.7 °C | 12.1 °C | 284.48 mm |
| April | 5.1 °C | 14.1 °C | 198.37 mm |
| May | 7.7 °C | 16.8 °C | 107.95 mm |
| June | 9.7 °C | 18.8 °C | 86.36 mm |
| July | 11.9 °C | 21.4 °C | 27.18 mm |
| August | 12 °C | 22.3 °C | 43.18 mm |
| September | 10.9 °C | 21.3 °C | 97.28 mm |
| October | 7.9 °C | 16.4 °C | 243.84 mm |
| November | 5.1 °C | 11.6 °C | 387.35 mm |
| December | 2.9 °C | 8.5 °C | 406.15 mm |
| Annual | 6.9 °C | 15.2 °C | 2534.41 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 40-50 Days |
| Plant Hardiness Zone | Zone 9a : -6.7°C to -3.9°C |
| Plant Hardiness Zone - 2012 | Zone 8b : -9.4°C to -6.7°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |