| 2023 Hardiness Zone: | Zone 6b: -5°F to 0°F | |
| 2012 Hardiness Zone: | Zone 6b: -5°F to 0°F | |
| 1990 Hardiness Zone: | Zone 1b: -15F to -10F | |
| 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: | 59d - Boston Basin | |
| Current Drought Status: | Exceptional Drought | |
| Heat Zone Days: | Rare Over 86°F |
Annual Climate Data for ZIP Code 02453 - Waltham, MA | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 17 | 19 | 27 | 37 | 47 | 56 | 62 | 60 | 52 | 41 | 33 | 23 | 39 |
| Avg Max Temp (°F) | 35 | 38 | 47 | 58 | 69 | 78 | 83 | 81 | 73 | 62 | 51 | 40 | 59 |
| Avg Precip (In.) | 4.29 | 3.48 | 4.24 | 4.11 | 3.65 | 3.58 | 3.61 | 3.73 | 3.83 | 4.17 | 4.48 | 4.15 | 47.31 |