The official National Weather Service forecast for Chester — 34.7049°N, 81.2143°W, population 8,611, 11.4 miles from I-77. Forecasts here are written by NWS GSP, this county’s forecast office.
| Chester County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 54 | 58 | 66 | 74 | 81 | 88 | 91 | 89 | 84 | 74 | 64 | 56 | 73 |
| Avg low °F | 31 | 35 | 41 | 49 | 57 | 65 | 69 | 68 | 62 | 50 | 39 | 34 | 50 |
| Precip in | 3.8 | 3.2 | 3.8 | 3.5 | 3.6 | 3.8 | 4.0 | 3.9 | 3.9 | 2.8 | 3.0 | 4.0 | 43.3 |
1996–2025 normals for Chester County — the climate division Chester sits in. All-time county record high 106.1°F (1983-08-22); record low -1.2°F (1985-01-22). Source: NOAA / National Weather Service.