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Right now in Viana do Castelo: clear skies, 18°C, feels like 18°C.
Expect a mostly clear week in Viana do Castelo, with temperatures staying fairly steady between 16°C and 29°C.
Daytime highs this week are about 5°C above the September average of 22°C.
Sunrise: 07:11 · Sunset: 19:52 · Day length: 12h 41m
Sea water: 17.3°C, practically unchanged all week
Wave height: 1.1m (min 0.8m on 2026-09-14, max 1.3m on 2026-09-16)
Viana do Castelo water temperature for the next 7 days · Sea temperature along the whole coast
Viana do Castelo sits where the Lima river meets the sea, between the Santa Luzia hill and the Minho coast. Across the river mouth waits Cabedelo beach, an open sweep of dunes where the afternoon northerly blows with a regularity that has made the city one of the country's best kitesurfing and windsurfing spots.
This is Portugal's greenest corner, and the climate explains it: winters are mild at 13–14 °C but among the rainiest on the Portuguese coast, with the bulk of the water falling between October and March. Summers settle at a pleasant 23–25 °C with plenty of sun, while the sea, fed by the northern upwelling, rarely warms beyond 15–17 °C.
| Month | Min (°C) | Max (°C) | Rainy days |
|---|---|---|---|
| January | 8.0 | 13.4 | 14.1 |
| February | 8.7 | 14.5 | 11.6 |
| March | 9.0 | 15.2 | 14.7 |
| April | 10.8 | 17.0 | 13.0 |
| May | 13.0 | 19.2 | 10.8 |
| June | 15.1 | 20.8 | 8.9 |
| July | 16.9 | 23.4 | 3.3 |
| August | 16.8 | 23.4 | 3.7 |
| September | 15.7 | 22.0 | 7.6 |
| October | 14.0 | 19.7 | 13.6 |
| November | 11.1 | 16.1 | 15.8 |
| December | 9.3 | 14.4 | 16.2 |
Going by Viana do Castelo's own averages, July is both the warmest and the most balanced month: highs near 23 °C and about 3 rainy days. The wettest is December with 16 rainy days.
Averages for 2016–2025. A rainy day is one with at least 1 mm of precipitation.
In August and September, with the water at 16–17 °C. The Minho coast shares the country's coldest sea with Porto, and even at the height of summer a swim takes some getting used to, or a thin wetsuit.
For the reliability of the wind. The summer thermal northerly arrives almost every afternoon at a steady strength, the open beach leaves plenty of room, and the Lima river mouth adds patches of flatter water, a combination rare in Europe.
In winter, yes: the Minho is among the rainiest regions of Portugal, with the Atlantic unloading mostly between October and March. In exchange, summer is fairly dry and sunny, and it is the winter rain that paints the region its distinctive green.