The official National Weather Service forecast for Harriman — 35.934°N, 84.5524°W, population 22,348, 2.9 miles from I-40.
| Roane County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 47 | 53 | 62 | 71 | 78 | 85 | 88 | 87 | 82 | 72 | 61 | 51 | 70 |
| Avg low °F | 29 | 33 | 39 | 46 | 55 | 63 | 67 | 66 | 60 | 48 | 37 | 32 | 48 |
| Precip in | 5.0 | 5.3 | 5.2 | 4.9 | 4.5 | 4.5 | 5.1 | 3.8 | 4.3 | 3.3 | 4.4 | 6.0 | 56.3 |
1996–2025 normals for Roane County — the climate division Harriman sits in. All-time county record high 105.2°F (1980-07-17); record low -15.0°F (1985-01-21). Source: NOAA / National Weather Service.