The official National Weather Service forecast for New Castle — 39.9289°N, 85.3702°W, population 18,555, 7.8 miles from I-70. Forecasts here are written by NWS IND, this county’s forecast office.
| Henry County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 35 | 39 | 50 | 63 | 73 | 81 | 84 | 82 | 78 | 65 | 51 | 40 | 62 |
| Avg low °F | 20 | 23 | 31 | 40 | 51 | 60 | 62 | 61 | 54 | 43 | 33 | 25 | 42 |
| Precip in | 3.1 | 2.6 | 3.7 | 4.5 | 4.8 | 5.1 | 4.2 | 3.5 | 3.1 | 3.1 | 3.0 | 3.3 | 44.0 |
1996–2025 normals for Henry County — the climate division New Castle sits in. All-time county record high 103.7°F (2012-06-29); record low -27.2°F (1994-01-19). Source: NOAA / National Weather Service.