| 2023 Hardiness Zone: | Zone 7a: 0°F to 5°F |
| 2012 Hardiness Zone: | Zone 6b: -5°F to 0°F |
| 1990 Hardiness Zone: | Zone 6b: -5F to 0F |
| Average First Frost Date: | Oct. 11 - Oct. 20 |
| Average Last Frost Date: | Apr. 21 - Apr. 30 |
| Koppen-Geiger Climate Zone: | Dfa - Humid Continental Hot Summers |
| Ecoregion: | 64b - Trap Rock and Conglomerate Uplands |
| Heat Zone Days: | 1 - 7 days Over 86°F |
Annual Climate Data for ZIP Code 08540 - Princeton, NJ | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 21 | 22 | 30 | 39 | 49 | 58 | 63 | 62 | 54 | 42 | 34 | 26 | 42 |
| Avg Max Temp (°F) | 38 | 41 | 51 | 62 | 72 | 81 | 86 | 84 | 76 | 65 | 54 | 43 | 63 |
| Avg Precip (In.) | 3.82 | 2.83 | 3.91 | 3.9 | 4.6 | 3.77 | 5.09 | 4.28 | 4.49 | 3.55 | 3.8 | 3.77 | 47.82 |