Your August weather guide
HotWeather in Lisbon in August
August is a good time for Lisbon if you want warm, mostly dry weather and can ease off when the afternoon gets hot. Average highs are around 27°C, nights fall to about 19°C, and there is only about 1 rainy day during the month. The catch is that the sea stays bracing rather than warm. It suits travellers who enjoy sunshine but do not need bath-like water for swimming.
Long-term climate averages for Lisbon, not a forecast · 1991-2020
Lisbon, month by month
Your snapshot
At a glance
The useful details for Lisbon.
- Average daytime high
- 26.6°C
- 9 in 10 days stay below 31°C
- Average night-time low
- 18.7°C
- coldest 10% of nights: 17°C or lower
- Compared with London
- +5.2°C
- London averages 21.4°C in August
- Sea temperature
- 19.2°C
- year to year: 18°C to 21°C
- Sunshine per day (est.)
- 10.2h
- 76% of 13.5 h of daylight
- Rainy days (1 mm+)
- 1
- 4 mm over the month
- Humidity
- 70%
- Days over 25°C
- 63%
- 18% over 30°C
- Record high 1991-2020
- 41.5°C
- 2018-08-04
- Record low 1991-2020
- 14.9°C
- 2019-08-03
- Flight from London
- ≈ 2 h 42 min
- 1549 km, short-haul (estimate for a direct flight)
Records are observed extremes within 1991-2020, not typical holiday conditions. Warm-day percentages are shares of days, not day counts.
How August compares
August is the 1st warmest month of the year in Lisbon and ranks 111th of 134 destinations we compare for August - see where else is hot in August. Within Portugal it is 10th of 13 (Portugal in August). Against London's average high of 21.4°C in August, Lisbon is 5.2°C warmer by day and 5.2°C warmer at night.
Daytime and night-time in August
The typical August day in Lisbon peaks at 26.6°C, but that is an average: the warmest 10% of days reach 31.2°C or more. About 63% of days top 25°C and 1 in 5 pass 30°C. Nights average 18.7°C; one night in ten drops to 17.0°C or lower, so pack a layer for evenings. Between 1991 and 2020 the hottest August day here reached 41.5°C (2018-08-04) and the coldest night 14.9°C (2019-08-03).
Rain in August
Dry (3 rainy days or fewer): about 1 days with 1 mm or more, 4 mm in total. Year to year it varies a lot - the wettest August was 2004 with 16 mm, the driest 1998 with 0 mm. Humidity averages 70%.
Sea temperature in August
The sea averages 19.2°C - bracing (18-22°c). Depending on the year it ranges from 18.2°C to 20.7°C. This is the warmest the sea gets here all year.
Sunshine and daylight
Around 10.2 hours of sunshine a day (estimated from cloud cover), 13.5 hours of daylight: the sun rises about 06:51 and sets about 20:32 local time in mid-August. Average cloud cover is 25%.
Is August a good time to visit Lisbon?
Yes - it is one of the better months: hot days, little rain and long sunny days. The best months for Lisbon on our scoring are July, August, September; months averaging 25°C or more: Jul, Aug.
Warm days, with hotter spells to plan around
August is Lisbon's warmest month, so go expecting summer heat rather than mild city-break weather. Days reach 30°C on 18% of occasions, and the hottest days can push above 31°C. Keep more active plans for the morning and leave room for shade or an indoor break at midday. Light, breathable clothing makes sense, along with a hat and sunscreen. Average nights are comfortable enough for spending time outside, though cooler nights can fall to 17°C or below, so a light layer is useful. If heat makes walking tiring for you, the average temperature should not be your only guide: allow flexibility for hotter afternoons.
Dry weather does not mean a warm sea
Rain is unlikely to be the main compromise in August. With so little expected, you can keep outdoor plans fairly flexible without building the trip around wet-weather alternatives. Pack sun protection ahead of bulky waterproofs, while remembering that a dry month is not a guarantee of completely rain-free days. Swimming is a different calculation: the sea averages 19.2°C, which feels bracing rather than comfortably warm. Its year-to-year range of 18°C to 21°C still falls short of warm swimming water. If you enjoy a refreshing dip, that may be fine; if you like lingering in the water, do not assume the hot air will make the sea feel equally inviting.
A little perspective
Lisbon through the year
August is highlighted. See how it compares with the rest of the year.
| Month | Day | Night | Sea | Sun/day | Rain mm | Rainy days | Days 25°C+ |
|---|---|---|---|---|---|---|---|
| January | 13.6°C | 9.1°C | 14.5°C | 4.6 | 68 | 9 | 0% |
| February | 14.4°C | 9.2°C | 14.0°C | 5.3 | 52 | 7 | 0% |
| March | 16.7°C | 10.8°C | 14.4°C | 5.9 | 53 | 8 | 0% |
| April | 18.1°C | 12.3°C | 15.3°C | 6.7 | 53 | 8 | 2% |
| May | 20.8°C | 14.4°C | 16.7°C | 7.8 | 44 | 6 | 17% |
| June | 23.9°C | 16.7°C | 18.0°C | 9.7 | 11 | 2 | 33% |
| Julybest | 26.0°C | 18.1°C | 18.7°C | 11.1 | 2 | 1 | 56% |
| AugustSelectedbest | 26.6°C | 18.7°C | 19.2°C | 10.2 | 4 | 1 | 63% |
| Septemberbest | 24.7°C | 17.8°C | 19.2°C | 7.9 | 29 | 4 | 42% |
| October | 21.2°C | 15.7°C | 18.2°C | 5.5 | 78 | 9 | 12% |
| November | 16.9°C | 12.4°C | 16.6°C | 4.8 | 84 | 10 | 0% |
| December | 14.5°C | 10.2°C | 15.2°C | 4.1 | 79 | 9 | 0% |
Day = average daytime high, night = average night-time low, 1991-2020.Sun is hours per day; rainy days count 1 mm or more.
Day, night and sea
Monthly average temperatures, 1991-2020
- Day
- Night
- Sea
Best months here
On warmth, low rainfall and sunshine, start with these.
Keep exploring
Similar in August
Closest matches on daytime temperature, sea temperature and sunshine, in other countries.
Hungary · 27°C by day
Budapest
Italy · 28°C by day
Lake Garda
Italy · 28°C by day
Milan
Spain · 27°C by day · sea 23°C
La Gomera
Spain · 27°C by day · sea 23°C
Tenerife
A little more detail
Lisbon in August FAQs
Plain answers, grounded in the averages.
Is Lisbon hot in August?
Lisbon is hot in August: the average daytime high is 26.6°C and nights average 18.7°C. About 63% of August days reach 25°C or more.
Can you swim in the sea in Lisbon in August?
The sea around Lisbon averages 19.2°C in August, which is bracing - fine for a quick dip, cool for long swims. Between 1991 and 2020 it ranged from 18°C to 21°C depending on the year.
How much does it rain in Lisbon in August?
Lisbon sees about 1 rainy days (1 mm or more) and 4 mm of rain in a typical August. The wettest August between 1991 and 2020 was 2004 (16 mm) and the driest was 1998 (0 mm).
How sunny is Lisbon in August?
Lisbon gets around 10.2 hours of sunshine a day in August out of 13.5 hours of daylight (estimated from average cloud cover).
How does Lisbon compare with the UK in August?
Lisbon is on average 5.2°C warmer than London by day in August (26.6°C against 21.4°C).
What is the hottest August on record in Lisbon?
Between 1991 and 2020 the hottest August day in Lisbon reached 41.5°C on 2018-08-04, and the coldest night dropped to 14.9°C on 2019-08-03.
How much warmer is Lisbon than London in August?
Lisbon's average daytime high is 26.6°C, compared with London's 21.4°C, a difference of 5.2°C. That is a noticeable step up for a UK traveller: pack for warmer afternoons and plan shade breaks rather than expecting typical London summer temperatures.
How much sunshine and daylight can I expect?
August brings about 10.2 hours of sunshine within 13.5 hours of daylight each day. That gives you plenty of scope for outdoor plans, but sunshine is not continuous. Use the cooler parts of the day for anything active.
About these averages
ERA5-Land climate reanalysis via Open-Meteo (11 km grid) and NOAA Coral Reef Watch 5 km sea temperatures, 1991-2020
Averages computed from daily values at Lisbon. Sea temperature from the nearest 5 km sea cell, 2.1 km from that point. Sunshine hours are estimated from average cloud cover.Records are the highest and lowest daily values in that 30-year period, not all-time records. These are climate averages, not a forecast for your trip. How we measure holiday weather
- Hot · 25°C+
- Warm · 20°C to below 25°C
- Mild · 15°C to below 20°C
- Cool · below 15°C