Your May weather guide
WarmWeather in Lisbon in May
May is a good time for Lisbon if you want comfortable city weather rather than strong heat or warm-water swimming. Average highs of 21°C suit days spent outdoors, while nights around 14°C call for a light layer. The catch is the sea: at about 17°C, it is cold rather than inviting for a leisurely swim. Expect some rain, but the balance favours travellers who prefer exploring in warmth without relying on hot weather.
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
- 20.8°C
- 9 in 10 days stay below 26°C
- Average night-time low
- 14.4°C
- coldest 10% of nights: 12°C or lower
- Compared with London
- +4.2°C
- London averages 16.6°C in May
- Sea temperature
- 16.7°C
- year to year: 16°C to 19°C
- Sunshine per day (est.)
- 7.8h
- 55% of 14.1 h of daylight
- Rainy days (1 mm+)
- 6
- 44 mm over the month
- Humidity
- 73%
- Days over 25°C
- 17%
- 2% over 30°C
- Record high 1991-2020
- 33.8°C
- 2019-05-30
- Record low 1991-2020
- 9.1°C
- 2018-05-01
- 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 May compares
May is the 6th warmest month of the year in Lisbon and ranks 106th of 134 destinations we compare for May - see where else is hot in May. Within Portugal it is 10th of 13 (Portugal in May). Against London's average high of 16.6°C in May, Lisbon is 4.2°C warmer by day and 6.1°C warmer at night.
Daytime and night-time in May
The typical May day in Lisbon peaks at 20.8°C, but that is an average: the warmest 10% of days reach 26.4°C or more. Roughly 1 in 6 days top 25°C and 1 in 67 pass 30°C. Nights average 14.4°C; one night in ten drops to 12.2°C or lower, so pack a layer for evenings - it is genuinely cool after dark. Between 1991 and 2020 the hottest May day here reached 33.8°C (2019-05-30) and the coldest night 9.1°C (2018-05-01).
Rain in May
Some rain (4-8 rainy days): about 6 days with 1 mm or more, 44 mm in total. Year to year it varies a lot - the wettest May was 2016 with 130 mm, the driest 2006 with 0 mm. Humidity averages 73%.
Sea temperature in May
The sea averages 16.7°C - too cold for most (under 18°c). Depending on the year it ranges from 15.5°C to 18.5°C. For the warmest sea here, come in August (19.2°C).
Sunshine and daylight
Around 7.8 hours of sunshine a day (estimated from cloud cover), 14.1 hours of daylight: the sun rises about 06:24 and sets about 20:41 local time in mid-May. Average cloud cover is 44%.
Is May a good time to visit Lisbon?
It is a reasonable choice: warm days. The best months for Lisbon on our scoring are July, August, September; months averaging 25°C or more: Jul, Aug.
Warm afternoons, cooler evenings
May usually feels warm rather than hot, making it a sensible choice if you find summer heat tiring. Days reach 25°C about 16% of the time, while 30°C is unusual, so do not plan around consistently hot afternoons. Still, lighter clothing and a break in the shade make sense when the temperature climbs at midday. There is about 7.8 hours of sunshine within 14.1 hours of daylight, giving you plenty of flexibility over when to head out. Keep a jumper or light jacket handy for evenings: the colder nights fall to 12.2°C or below, which can feel cool after a warm afternoon.
Allow for rain, and treat swimming as optional
Rain is a consideration, not a reason on its own to rule May out. About 6 rainy days means a light waterproof and room to adjust your plans are sensible, rather than assuming every day will stay dry. You can plan time outdoors, but avoid making the whole trip depend on clear skies. The sea is the bigger limitation for a beach-focused holiday: its average temperature is 16.7°C, with a range of 16°C to 18°C between years. That is cold water, so May suits travellers who are happy to spend time by the coast without expecting comfortable swimming. Pack for mixed conditions rather than a purely summer wardrobe.
A little perspective
Lisbon through the year
May 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% |
| MaySelected | 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% |
| Augustbest | 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 May
Closest matches on daytime temperature, sea temperature and sunshine, in other countries.
Spain · 21°C by day · sea 17°C
Barcelona
France · 21°C by day · sea 17°C
Nice
Croatia · 20°C by day · sea 17°C
Pula
Spain · 22°C by day · sea 17°C
Lloret de Mar
Spain · 22°C by day · sea 17°C
Marbella
A little more detail
Lisbon in May FAQs
Plain answers, grounded in the averages.
Is Lisbon hot in May?
Lisbon is warm in May: the average daytime high is 20.8°C and nights average 14.4°C. Roughly 1 in 6 May days reach 25°C.
Can you swim in the sea in Lisbon in May?
The sea around Lisbon averages 16.7°C in May, which is cold for swimming without a wetsuit. Between 1991 and 2020 it ranged from 16°C to 19°C depending on the year.
How much does it rain in Lisbon in May?
Lisbon sees about 6 rainy days (1 mm or more) and 44 mm of rain in a typical May. The wettest May between 1991 and 2020 was 2016 (130 mm) and the driest was 2006 (0 mm).
How sunny is Lisbon in May?
Lisbon gets around 7.8 hours of sunshine a day in May out of 14.1 hours of daylight (estimated from average cloud cover).
How does Lisbon compare with the UK in May?
Lisbon is on average 4.2°C warmer than London by day in May (20.8°C against 16.6°C).
What is the hottest May on record in Lisbon?
Between 1991 and 2020 the hottest May day in Lisbon reached 33.8°C on 2019-05-30, and the coldest night dropped to 9.1°C on 2018-05-01.
How much warmer is Lisbon than London in May?
Lisbon's average daytime high is 20.8°C, compared with London's 16.6°C, a difference of 4.2°C. That makes it a useful step up in warmth for a UK traveller, though you should still bring a layer for evenings rather than pack only summer clothes.
Should I choose May or wait until summer?
Choose May if comfortable warmth matters more than reliable heat and you can accept some rain and cold sea water. July, August and September are stronger overall weather choices. May makes sense for a city-focused trip where swimming is optional.
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