The official National Weather Service forecast for Jonesboro — 40.4798°N, 85.6278°W, 8 miles from I-69. Forecasts here are written by NWS IWX, this county’s forecast office.
| Grant County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 34 | 38 | 50 | 62 | 73 | 82 | 84 | 82 | 78 | 65 | 51 | 39 | 62 |
| Avg low °F | 19 | 22 | 31 | 40 | 51 | 60 | 63 | 61 | 54 | 44 | 33 | 24 | 42 |
| Precip in | 2.7 | 2.4 | 3.1 | 3.8 | 4.4 | 4.8 | 4.0 | 3.9 | 3.3 | 3.1 | 2.8 | 2.8 | 41.1 |
1996–2025 normals for Grant County — the climate division Jonesboro sits in. All-time county record high 102.9°F (2012-06-29); record low -22.8°F (1985-01-20). Source: NOAA / National Weather Service.