| 2023 Hardiness Zone: | Zone 7b: 5°F to 10°F |
| 2012 Hardiness Zone: | Zone 7a: 0°F to 5°F |
| 1990 Hardiness Zone: | Zone 7a: 0F to 5F |
| Average First Frost Date: | Oct. 21 - Oct. 31 |
| Average Last Frost Date: | Apr. 21 - Apr. 30 |
| Koppen-Geiger Climate Zone: | Dfb - Humid Continental Mild Summer, Wet All Year |
| Ecoregion: | 59g - Long Island Sound Coastal Lowland |
| Heat Zone Days: | Rare Over 86°F |
Annual Climate Data for ZIP Code 11777 - Port Jefferson, NY | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 24 | 25 | 31 | 40 | 49 | 59 | 64 | 64 | 57 | 47 | 38 | 29 | 44 |
| Avg Max Temp (°F) | 39 | 41 | 50 | 60 | 71 | 79 | 84 | 82 | 75 | 65 | 55 | 44 | 62 |
| Avg Precip (In.) | 4 | 2.99 | 4.22 | 4.21 | 4.01 | 3.83 | 3.61 | 3.94 | 3.73 | 3.78 | 3.9 | 3.96 | 46.19 |