| 2023 Hardiness Zone: | Zone 7a: 0°F to 5°F |
| 2012 Hardiness Zone: | Zone 6b: -5°F to 0°F Zone 7a: 0°F to 5°F |
| 1990 Hardiness Zone: | Zone 6b: -5F to 0F |
| Average First Frost Date: | October 21 - 31 |
| Average Last Frost Date: | April 21 - 30 |
| Koppen-Geiger Climate Zone: | Dfa - Humid Continental Hot Summers |
| Ecoregion: | 59e - Narragansett/Bristol Lowland |
| Heat Zone Days: | Rare Over 86°F |
Annual Climate Data for ZIP Code 02871 - Portsmouth, RI | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 22 | 23 | 30 | 38 | 48 | 57 | 63 | 63 | 56 | 45 | 37 | 27 | 42 |
| Avg Max Temp (°F) | 38 | 39 | 46 | 56 | 66 | 75 | 80 | 79 | 72 | 62 | 52 | 42 | 59 |
| Avg Precip (In.) | 4.41 | 3.58 | 4.55 | 4.34 | 3.62 | 3.3 | 3.12 | 3.86 | 3.74 | 3.79 | 4.56 | 4.39 | 47.27 |