The official National Weather Service forecast for New London — 43.414°N, 71.9851°W, 1.8 miles from I-89.
| Merrimack County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 31 | 34 | 43 | 56 | 68 | 76 | 81 | 80 | 72 | 59 | 47 | 36 | 57 |
| Avg low °F | 13 | 14 | 22 | 33 | 44 | 53 | 59 | 56 | 49 | 38 | 28 | 19 | 36 |
| Precip in | 3.3 | 3.2 | 3.7 | 4.0 | 4.0 | 4.5 | 4.4 | 3.8 | 3.9 | 4.9 | 3.6 | 4.3 | 47.6 |
1996–2025 normals for Merrimack County — the climate division New London sits in. All-time county record high 97.6°F (2025-06-25); record low -29.2°F (1957-01-14). Source: NOAA / National Weather Service.