The official National Weather Service forecast for Fitchburg — 42.5834°N, 71.8023°W, 5.1 miles from I-190.
| Worcester County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 34 | 37 | 45 | 58 | 69 | 77 | 82 | 80 | 73 | 61 | 50 | 39 | 59 |
| Avg low °F | 16 | 18 | 25 | 35 | 45 | 55 | 61 | 59 | 51 | 40 | 31 | 23 | 38 |
| Precip in | 3.7 | 3.4 | 4.1 | 4.3 | 4.0 | 4.3 | 4.2 | 4.0 | 4.2 | 4.9 | 3.5 | 4.5 | 49.1 |
1996–2025 normals for Worcester County — the climate division Fitchburg sits in. All-time county record high 98.1°F (2011-07-23); record low -21.4°F (1984-01-22). Source: NOAA / National Weather Service.