The official National Weather Service forecast for Newcastle — 35.2473°N, 97.5998°W, 2 miles from I-44. Forecasts here are written by NWS OUN, this county’s forecast office.
| McClain County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 51 | 55 | 65 | 73 | 80 | 89 | 94 | 94 | 87 | 75 | 63 | 53 | 73 |
| Avg low °F | 28 | 31 | 41 | 49 | 58 | 67 | 71 | 70 | 62 | 51 | 40 | 31 | 50 |
| Precip in | 1.5 | 1.6 | 2.8 | 4.0 | 5.3 | 4.6 | 3.0 | 3.2 | 3.0 | 3.6 | 2.1 | 1.8 | 36.5 |
1996–2025 normals for McClain County — the climate division Newcastle sits in. All-time county record high 110.8°F (2012-08-02); record low -8.9°F (1989-12-23). Source: NOAA / National Weather Service.