The official National Weather Service forecast for New Harmony — 37.4794°N, 113.3097°W, 4.9 miles from I-15. Forecasts here are written by NWS SLC, this county’s forecast office.
| Washington County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 48 | 51 | 59 | 66 | 76 | 88 | 93 | 90 | 83 | 70 | 58 | 48 | 69 |
| Avg low °F | 28 | 30 | 35 | 41 | 49 | 59 | 65 | 64 | 56 | 45 | 35 | 28 | 45 |
| Precip in | 1.7 | 1.9 | 1.6 | 1.0 | 0.6 | 0.3 | 1.1 | 1.4 | 1.1 | 1.3 | 1.1 | 1.6 | 14.7 |
1996–2025 normals for Washington County — the climate division New Harmony sits in. All-time county record high 106.5°F (2021-07-11); record low -8.0°F (1990-12-23). Source: NOAA / National Weather Service.