The official National Weather Service forecast for Iowa City — 41.6611°N, 91.5302°W, population 126,810, 4.4 miles from I-80.
| Johnson County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 30 | 34 | 48 | 62 | 72 | 82 | 85 | 83 | 77 | 64 | 49 | 35 | 60 |
| Avg low °F | 13 | 16 | 28 | 38 | 50 | 60 | 64 | 61 | 53 | 41 | 29 | 19 | 39 |
| Precip in | 1.2 | 1.4 | 2.2 | 3.5 | 4.6 | 5.2 | 4.1 | 4.0 | 3.2 | 3.2 | 1.8 | 1.6 | 36.0 |
1996–2025 normals for Johnson County — the climate division Iowa City sits in. All-time county record high 104.4°F (2012-07-24); record low -31.7°F (2019-01-31). Source: NOAA / National Weather Service.