The official National Weather Service forecast for Glen Allen — 33.9151°N, 87.7417°W, 4.3 miles from I-22. Forecasts here are written by NWS BMX, this county’s forecast office.
| Marion County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 52 | 57 | 66 | 74 | 81 | 87 | 90 | 90 | 85 | 75 | 64 | 55 | 73 |
| Avg low °F | 31 | 35 | 41 | 48 | 57 | 65 | 69 | 68 | 62 | 50 | 39 | 34 | 50 |
| Precip in | 5.7 | 5.8 | 5.8 | 5.8 | 4.9 | 5.0 | 5.1 | 4.3 | 3.9 | 3.8 | 4.3 | 6.2 | 60.6 |
1996–2025 normals for Marion County — the climate division Glen Allen sits in. All-time county record high 107.3°F (1952-07-29); record low -12.3°F (1966-01-30). Source: NOAA / National Weather Service.