The official National Weather Service forecast for Portland — 40.4345°N, 84.9778°W, population 6,364, 30.6 miles from I-69. Forecasts here are written by NWS IWX, this county’s forecast office.
| Jay County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 34 | 38 | 50 | 62 | 73 | 82 | 84 | 83 | 78 | 65 | 51 | 39 | 62 |
| Avg low °F | 19 | 22 | 31 | 40 | 51 | 60 | 63 | 61 | 54 | 43 | 33 | 25 | 42 |
| Precip in | 2.7 | 2.4 | 3.2 | 4.0 | 4.4 | 4.4 | 4.0 | 3.6 | 3.0 | 2.9 | 2.8 | 2.8 | 40.2 |
1996–2025 normals for Jay County — the climate division Portland sits in. All-time county record high 104.1°F (2012-06-29); record low -24.1°F (1994-01-19). Source: NOAA / National Weather Service.