| 2023 Hardiness Zone: | Zone 8b: 15°F to 20°F Zone 9a: 20°F to 25°F |
| 2012 Hardiness Zone: | Zone 8b: 15°F to 20°F |
| 1990 Hardiness Zone: | Zone 8b: 15F to 20F |
| Average First Frost Date: | Nov. 11 - Nov. 20 |
| Average Last Frost Date: | Mar. 11 - Mar. 20 |
| Koppen-Geiger Climate Zone: | Csb - Warm-Summer Mediterranean Climate |
| Ecoregion: | 3d - Valley Foothills |
| Heat Zone Days: | Rare Over 86°F |
Annual Climate Data for ZIP Code 97034 - Lake Oswego, OR | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 35 | 37 | 39 | 42 | 47 | 52 | 55 | 56 | 52 | 45 | 40 | 35 | 44 |
| Avg Max Temp (°F) | 47 | 52 | 57 | 62 | 68 | 74 | 81 | 81 | 76 | 65 | 53 | 46 | 63 |
| Avg Precip (In.) | 6.28 | 5.05 | 4.46 | 3 | 2.45 | 1.69 | .68 | .92 | 1.76 | 3.48 | 6.22 | 6.92 | 42.92 |