The official National Weather Service forecast for Mount Ayr — 40.952°N, 87.2992°W, 3.9 miles from I-65. Forecasts here are written by NWS LOT, this county’s forecast office.
| Newton County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 33 | 37 | 50 | 62 | 73 | 82 | 84 | 83 | 78 | 66 | 51 | 38 | 61 |
| Avg low °F | 17 | 20 | 30 | 38 | 50 | 60 | 63 | 61 | 53 | 43 | 32 | 23 | 41 |
| Precip in | 2.2 | 2.0 | 2.6 | 3.6 | 4.5 | 5.0 | 4.6 | 4.0 | 2.9 | 3.2 | 2.3 | 2.3 | 39.2 |
1996–2025 normals for Newton County — the climate division Mount Ayr sits in. All-time county record high 102.8°F (1988-08-18); record low -24.8°F (1985-01-20). Source: NOAA / National Weather Service.