The official National Weather Service forecast for West Haven — 45.5176°N, 122.7695°W, 5.1 miles from I-5. Forecasts here are written by NWS PQR, this county’s forecast office.
| Washington County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 46 | 48 | 52 | 58 | 65 | 71 | 79 | 79 | 73 | 61 | 51 | 45 | 61 |
| Avg low °F | 35 | 34 | 36 | 39 | 44 | 49 | 53 | 54 | 50 | 43 | 38 | 34 | 42 |
| Precip in | 8.6 | 6.5 | 6.2 | 3.8 | 2.6 | 1.6 | 0.3 | 0.6 | 1.9 | 4.8 | 8.5 | 10.4 | 55.8 |
1996–2025 normals for Washington County — the climate division West Haven sits in. All-time county record high 106.3°F (2021-06-28); record low 2.9°F (1972-12-08). Source: NOAA / National Weather Service.