The official National Weather Service forecast for Jefferson — 42.0153°N, 94.3775°W, 35.7 miles from I-80.
| Greene County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 29 | 33 | 47 | 61 | 72 | 82 | 84 | 82 | 77 | 64 | 48 | 34 | 59 |
| Avg low °F | 11 | 15 | 27 | 37 | 49 | 60 | 63 | 60 | 52 | 40 | 28 | 17 | 38 |
| Precip in | 0.9 | 1.1 | 2.0 | 3.5 | 5.0 | 5.2 | 4.1 | 4.1 | 3.1 | 2.7 | 1.5 | 1.3 | 34.5 |
1996–2025 normals for Greene County — the climate division Jefferson sits in. All-time county record high 103.9°F (1955-07-31); record low -27.5°F (1996-02-03). Source: NOAA / National Weather Service.