Monthly climate guide
Viana do Castelo weather in September
Expect warm weather in Viana do Castelo in September: afternoons reach about 25°C (77°F), while nights drop to around 16°C (60°F). Around 52 mm of rain falls over the month (some rain), and skies are mostly sunny. Daytime highs are about the same as August and 4°C warmer than October.
What stands out in September
- Temperatures are falling — expect highs around 4°C lower by October.
- Seasonally, September counts as early autumn in Viana do Castelo.
- September is Viana do Castelo's third warmest month.
- It's one of the drier months, with about 41% less rain than Viana do Castelo's average.
Avg high
25°C
77°F
Avg low
16°C
60°F
Rainfall
52 mm
some rain
Humidity
69%
relative
Sky
34%
cloud · mostly sunny
Viana do Castelo weather by month
Show the monthly averages as a table
| Month | Avg high | Avg low | Rain | Humidity | Cloud cover |
|---|---|---|---|---|---|
| January | 13°C / 55°F | 7°C / 45°F | 141 mm | 87% | 54% |
| February | 14°C / 56°F | 7°C / 45°F | 102 mm | 84% | 51% |
| March | 15°C / 60°F | 8°C / 47°F | 111 mm | 81% | 49% |
| April | 17°C / 63°F | 10°C / 50°F | 104 mm | 81% | 52% |
| May | 20°C / 68°F | 12°C / 54°F | 70 mm | 78% | 43% |
| June | 22°C / 72°F | 14°C / 57°F | 34 mm | 74% | 41% |
| July | 26°C / 78°F | 16°C / 60°F | 13 mm | 69% | 28% |
| August | 26°C / 78°F | 16°C / 61°F | 25 mm | 69% | 30% |
| September | 25°C / 77°F | 16°C / 60°F | 52 mm | 69% | 34% |
| October | 21°C / 70°F | 14°C / 56°F | 120 mm | 76% | 46% |
| November | 16°C / 61°F | 10°C / 50°F | 152 mm | 84% | 53% |
| December | 14°C / 57°F | 8°C / 47°F | 132 mm | 86% | 54% |
What to pack for September
- T-shirts plus a light layer for the evening
- Comfortable trainers or sandals for long walks
- A small travel umbrella, just in case
- Sunglasses
Is September a good time to visit Viana do Castelo?
Compare the months in the chart above to find your ideal window.
Best time to visit Viana do Castelo →Other Portugal cities in September
Cite or embed this data
Writing about this destination? Copy a ready-made citation or embed a live widget — free, just keep the link.
Viana do Castelo weather in September. WeatherCompare, 2026 (NASA POWER / ERA5, 2011–2020 monthly averages). https://weathercompare.eu/weather/portugal/viana-do-castelo/september
<a href="https://weathercompare.eu/weather/portugal/viana-do-castelo/september">Viana do Castelo weather in September</a> (WeatherCompare)
<iframe src="https://weathercompare.eu/embed/portugal/viana-do-castelo" width="300" height="160" style="border:0;border-radius:12px" loading="lazy" title="Viana do Castelo weather in September"></iframe> <p style="font-size:12px"><a href="https://weathercompare.eu/weather/portugal/viana-do-castelo/september">Viana do Castelo weather in September</a> – WeatherCompare</p>
Viana do Castelo in September: quick answers
Is September a good time to visit Viana do Castelo?
September is a reasonable time for Viana do Castelo: highs around 25°C and about 52 mm of rain, though not one of the three best months.
How warm is Viana do Castelo in September?
Average highs are about 25°C (77°F) and average lows about 16°C (60°F), based on 10 years of daily data.
Does it rain a lot in Viana do Castelo in September?
Viana do Castelo typically gets around 52 mm of rain in September — some rain.
Figures are long-term averages for the area around Viana do Castelo (NASA POWER / ERA5, 2011–2020), not a forecast for a specific year. For upcoming days, see the live multi-source forecast.