The official National Weather Service forecast for Marietta — 39.4153°N, 81.4548°W, population 21,723, 1.6 miles from I-77.
| Washington County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 39 | 44 | 54 | 66 | 75 | 82 | 85 | 84 | 79 | 67 | 55 | 44 | 64 |
| Avg low °F | 23 | 25 | 32 | 41 | 50 | 59 | 63 | 62 | 55 | 44 | 33 | 28 | 43 |
| Precip in | 3.4 | 3.2 | 3.7 | 3.9 | 4.5 | 4.7 | 4.5 | 3.6 | 3.4 | 3.1 | 2.9 | 3.4 | 44.3 |
1996–2025 normals for Washington County — the climate division Marietta sits in. All-time county record high 101.2°F (2012-07-08); record low -26.3°F (1994-01-20). Source: NOAA / National Weather Service.