Viana do Castelo in Summer
In summer (June, July and August), Viana do Castelo sees average daytime highs around 23°C and overnight lows near 15°C, with 132 mm of rain over about 16 wet days across the season. It is the warmest season of the year and the driest season of the year.
Over the season highs climb from about 20°C in early June to 23°C by late August. The sky is clear or mostly clear about 59% of the time across summer, and the air most often feels comfortable.
Summer is Viana do Castelo's best season of the year to visit on our travel score. For the whole year in context, see Viana do Castelo's year-round climate.
- Avg daytime high
- 23°C
- warmest season of the year
- Avg overnight low
- 15°C
- Rainfall
- 132 mm
- 16 wet days
- Avg wind
- 12 km/h
- Travel score
- 8.0
- best season of the year
- Months
- Jun · Jul · Aug
Temperature in Viana do Castelo in Summer
Over the season highs climb from about 20°C in early June to 23°C by late August.
A typical summer day in Viana do Castelo reaches about 23°C and drops to 15°C overnight. The warmest of the three months is August, the coolest June.
Viana do Castelo weather by month
How the three summer months (June, July and August) compare with the rest of the year — the season's months are highlighted.
| Month | High / Low (°C) | Rainfall (mm) | Wet days | Daylight (hours) | Travel score |
|---|---|---|---|---|---|
| Jan | 13° / 7° | 218 | 13.6 | 9.3 | 3.3 |
| Feb | 14° / 7° | 142 | 10.4 | 10.3 | 3.9 |
| Mar | 15° / 8° | 165 | 11.3 | 11.7 | 4.7 |
| Apr | 17° / 10° | 154 | 13 | 13.1 | 5.0 |
| May | 19° / 12° | 133 | 11.8 | 14.3 | 5.9 |
| Jun | 21° / 14° | 56 | 6.9 | 15 | 7.2 |
| Jul | 23° / 16° | 32 | 4.4 | 14.7 | 8.4 |
| Aug | 24° / 16° | 45 | 5 | 13.7 | 8.3 |
| Sep | 22° / 15° | 89 | 7.4 | 12.3 | 7.3 |
| Oct | 19° / 13° | 232 | 13.2 | 10.9 | 5.7 |
| Nov | 15° / 10° | 232 | 14.2 | 9.6 | 4.3 |
| Dec | 13° / 8° | 227 | 14.1 | 9 | 3.5 |
Cloud cover in Summer
The sky is clear or mostly clear about 59% of the time across summer.
Chance of precipitation in Summer
Viana do Castelo gets around 132 mm of rain over 16 wet days across summer. The line is the day-by-day chance of measurable precipitation.
Humidity in Summer
Most of summer feels comfortable — the stacked bands show each day's mix of comfort levels, read off the dew point.
Wind in Summer
Winds average 12 km/h across summer.
Sunrise & sunset in Summer
Daylight runs from about 14 h 48 min in early June to 13 hours by late August. The lit band spans sunrise to sunset each day.
Solar energy in Summer
Average shortwave solar energy reaching the ground each day across summer, about 7.0 kWh/m².
Hazard calendar for Viana do Castelo
None of Viana do Castelo's seasonal hazards peak in summer. The full-year calendar below shows when the rainy season, cyclone risk and dust haze do.
Viana do Castelo's rainy season runs October–May, when most of the year's rain falls.
Is summer a good time to visit Viana do Castelo?
Our two travel scores rate summer for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal), averaged across the three months.
summer is one of the better times to visit Viana do Castelo for general sightseeing.
What to pack for Viana do Castelo in Summer
From summer's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In summer, Viana do Castelo sees daytime highs around 23°C and nights near 15°C. Pack sun protection. Worth having: light clothes. About 16 days see rain.
Sea temperature near Viana do Castelo in Summer
The nearest coast averages about 17°C across summer — the other half of the beach question. The full-year curve and swim-comfort zones are below.
The sea offshore is warmest in August at about 17°C and coldest in February near 13°C.
The water stays below 20°C all year — cool enough that most swimmers want a wetsuit.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sea temperature (°C) | 14 | 13 | 14 | 14 | 15 | 17 | 17 | 17 | 17 | 17 | 16 | 15 |
| Comfort | Bracing | Bracing | Bracing | Bracing | Cool | Cool | Cool | Cool | Cool | Cool | Cool | Bracing |
| Sea temperature (°C) | Comfort | |
|---|---|---|
| Jan | 14 | Bracing |
| Feb | 13 | Bracing |
| Mar | 14 | Bracing |
| Apr | 14 | Bracing |
| May | 15 | Cool |
| Jun | 17 | Cool |
| Jul | 17 | Cool |
| Aug | 17 | Cool |
| Sep | 17 | Cool |
| Oct | 17 | Cool |
| Nov | 16 | Cool |
| Dec | 15 | Bracing |
UV index in Viana do Castelo in Summer
Clear-sky midday UV across summer averages around 9 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.
Under clear skies, the midday UV index in Viana do Castelo peaks around June 23 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 20 at about 2 (low).
The index reaches 3 or more — the level where the WHO recommends sun protection — in 8 months of the year.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 2 | 3 | 5 | 6 | 7 | 9 | 9 | 8 | 6 | 4 | 2 | 2 |
| Level | Low | Moderate | Moderate | High | High | Very high | Very high | Very high | High | Moderate | Moderate | Low |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 2 | Low |
| Feb | 3 | Moderate |
| Mar | 5 | Moderate |
| Apr | 6 | High |
| May | 7 | High |
| Jun | 9 | Very high |
| Jul | 9 | Very high |
| Aug | 8 | Very high |
| Sep | 6 | High |
| Oct | 4 | Moderate |
| Nov | 2 | Moderate |
| Dec | 2 | Low |
Where is Viana do Castelo?
Viana do Castelo sits at 41.7°N, 8.8°W, 12 m above sea level, in Portugal. The nearest listed city is Esposende, 18 km away.
Topography around Viana do Castelo
How much the land rises and falls, and what covers it, within 3, 16 and 80 km of Viana do Castelo.
Within 3 km, the terrain around Viana do Castelo has significant variations in elevation — a maximum elevation change of 300 m around an average of 29 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 793 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,517 m.
The land around Viana do Castelo is covered by water (37%), trees (23%) and artificial surfaces (22%) within 3 km, water (47%) and trees (29%) within 16 km, and trees (38%), water (32%) and grassland (22%) within 80 km.
Portugal travel facts
- Travel advisory
- Level 1
- Exercise Normal Precautions
- Power plugs
- Type C / E / F
- 230 V · 50 Hz
- Prices
- ≈ 60% of US
- price level, 2025
- GDP per capita
- $32,082
- 2025
- Happiness
- 6.0 / 10
- World Happiness, 2025
- Safe drinking water
- 95%
- of population, 2024
- Homicide rate
- 0.7
- per 100k, 2022
- Road deaths
- 8.2
- per 100k/yr, 2019
- Income group
- High
- World Bank
- English
- Very high
- EF EPI 612
- Religion
Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.
Data sources
Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Viana do Castelo (41.6932°, -8.8329°, elevation 12 m), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google.