The official National Weather Service forecast for Dayton — 39.2371°N, 119.593°W, 9 miles from I-580. Forecasts here are written by NWS REV, this county’s forecast office.
| Lyon County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 45 | 49 | 56 | 63 | 72 | 83 | 91 | 89 | 80 | 67 | 55 | 45 | 66 |
| Avg low °F | 22 | 25 | 29 | 34 | 42 | 50 | 57 | 55 | 47 | 36 | 27 | 22 | 37 |
| Precip in | 1.2 | 1.0 | 0.9 | 0.6 | 0.7 | 0.4 | 0.3 | 0.3 | 0.3 | 0.6 | 0.6 | 1.1 | 8.0 |
1996–2025 normals for Lyon County — the climate division Dayton sits in. All-time county record high 103.5°F (2002-07-11); record low -18.0°F (1990-12-22). Source: NOAA / National Weather Service.