The official National Weather Service forecast for Portland — 47.4983°N, 97.3704°W, 13.1 miles from I-29.
| Traill County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 17 | 21 | 35 | 52 | 67 | 77 | 82 | 80 | 72 | 56 | 38 | 23 | 52 |
| Avg low °F | 0 | 2 | 16 | 31 | 43 | 55 | 59 | 56 | 48 | 35 | 21 | 7 | 31 |
| Precip in | 0.5 | 0.5 | 0.9 | 1.5 | 3.1 | 3.7 | 3.1 | 2.7 | 2.4 | 2.1 | 0.8 | 0.8 | 22.1 |
1996–2025 normals for Traill County — the climate division Portland sits in. All-time county record high 104.5°F (1983-08-08); record low -38.1°F (1996-02-02). Source: NOAA / National Weather Service.