| 2023 Hardiness Zone: | Zone 8b: 15°F to 20°F Zone 8a: 10°F to 15°F |
| 2012 Hardiness Zone: | Zone 8b: 15°F to 20°F Zone 8a: 10°F to 15°F |
| 1990 Hardiness Zone: | Zone 8b: 15F to 20F |
| Average First Frost Date: | Oct. 21 - Oct. 31 |
| Average Last Frost Date: | May 1 - May 10 |
| Koppen-Geiger Climate Zone: | Csb - Warm-Summer Mediterranean Climate |
| Ecoregion: | 2h - Cowlitz/Chehalis Foothills |
| Heat Zone Days: | Rare Over 86°F |
Annual Climate Data for ZIP Code 98611 - Castle Rock, WA | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 33 | 34 | 36 | 39 | 44 | 48 | 51 | 51 | 47 | 42 | 37 | 34 | 41 |
| Avg Max Temp (°F) | 45 | 50 | 55 | 60 | 66 | 71 | 77 | 78 | 73 | 62 | 51 | 45 | 61 |
| Avg Precip (In.) | 6.24 | 5.56 | 4.96 | 3.61 | 2.58 | 2.15 | .96 | 1.17 | 2.18 | 3.64 | 7.1 | 7.31 | 47.46 |