The official National Weather Service forecast for Derry — 42.8806°N, 71.3273°W, 1.2 miles from I-93.
| Rockingham County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 34 | 37 | 45 | 57 | 68 | 77 | 82 | 81 | 74 | 61 | 50 | 39 | 59 |
| Avg low °F | 16 | 17 | 25 | 35 | 45 | 55 | 61 | 59 | 52 | 40 | 30 | 22 | 38 |
| Precip in | 3.4 | 3.2 | 4.1 | 4.2 | 4.0 | 4.3 | 4.0 | 3.6 | 3.8 | 4.8 | 3.6 | 4.4 | 47.4 |
1996–2025 normals for Rockingham County — the climate division Derry sits in. All-time county record high 100.3°F (2025-06-25); record low -21.6°F (1957-01-18). Source: NOAA / National Weather Service.