The official National Weather Service forecast for Waterloo — 42.4928°N, 92.343°W, population 114,139, 1.5 miles from I-380.
| Black Hawk County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 27 | 32 | 46 | 60 | 71 | 81 | 83 | 81 | 76 | 63 | 47 | 33 | 58 |
| Avg low °F | 10 | 13 | 26 | 36 | 48 | 59 | 62 | 59 | 52 | 39 | 27 | 16 | 37 |
| Precip in | 1.2 | 1.2 | 1.9 | 3.6 | 4.8 | 5.7 | 4.2 | 3.9 | 3.3 | 2.9 | 1.8 | 1.5 | 36.0 |
1996–2025 normals for Black Hawk County — the climate division Waterloo sits in. All-time county record high 103.1°F (1988-08-18); record low -30.9°F (2019-01-31). Source: NOAA / National Weather Service.