Best Time to Visit Lisbon

The short answer: June, then September

Lisbon has two good windows rather than one, and they sit either side of the summer peak. June gets you the dry weather before the August crowds; September gets you the same warmth after them, with a sea that has had all summer to warm up.

1. June averages a 26.1°C high, a 16.8°C low and just 14.1 mm of rain (IPMA, Lisboa / Instituto Geofísico, 1991-2020 normals).
2. September averages a 26.6°C high — marginally warmer than June — with 38.6 mm of rain.
3. September delivers 19.5 days above 25°C, against June’s 16.9.
4. Neither month is uncomfortably hot: June averages 0.6 days above 35°C and September 0.5.
5. The Santo António street parties fall in mid-June, which fills the Alfama and Graça districts for several nights.

If the choice is purely about weather, September edges it. If it is about price and quiet, June is the better bet, because September is when the rest of Europe has worked out that Lisbon is still warm.

Lisbon month by month, with the numbers

These are the 1991-2020 climate normals for Lisboa / Instituto Geofísico, published by IPMA, the Portuguese meteorological institute. "Warm days" counts days where the maximum reached 25°C; "hot days" counts days that reached 30°C.

The rain column is the one that decides a Lisbon trip. Four months — October, November, December and January — carry more than 100 mm each and together account for over half the annual total of 793.5 mm.

The wet season is autumn, not winter

Lisbon is sold as a year-round city break, and the mild winter temperatures support that. The rainfall does not. The wettest month is November, and the second wettest is October — both wetter than January, which is the month most people picture when they imagine a rainy Lisbon.

1. November averages 133.9 mm, the wettest month of the Lisbon year.
2. October averages 110.6 mm, the second wettest, and more than January’s 103.8 mm.
3. Rainfall multiplies almost threefold between September (38.6 mm) and October (110.6 mm) — the sharpest month-to-month change in the Lisbon year.
4. July averages 2.6 mm and August 5.4 mm, so the summer is effectively rainless.
5. The four wettest months together carry more than half of the 793.5 mm annual total.

The practical consequence is that a late-October or November trip needs an indoor plan, and Lisbon is a good city for one — but book it knowing that, rather than discovering it.

Summer in Lisbon is a hill problem, not a heat problem

On paper a 28.8°C August high is mild by Iberian standards — Seville and Córdoba are far hotter. What the number does not capture is that Lisbon is built on hills, and the walking is relentlessly up and down. The heat is felt on the climbs, not on the thermometer.

1. August averages 27.4 days above 25°C — almost the whole month.
2. August also averages 10.2 days above 30°C and 1.8 above 35°C.
3. August nights stay at or above 20°C on 6.8 days, so the flat does not cool down overnight unless it has air conditioning.
4. The highest temperature ever recorded at this station is 43.3°C, on 4 August 2018.
5. Miradouro-to-miradouro walking routes climb and descend repeatedly, which is what turns a 28°C day into a hard one.

Two adjustments make August workable: start walking before 10am, and use the trams and funiculars for the climbs rather than treating them as a novelty to be photographed and then walked past.

Best time for each kind of Lisbon trip

The best month depends on what the trip is for. These windows follow the IPMA normals rather than a general ranking.

1. Walking the city and its hills: May or October, when mean highs sit at 23.1°C and 22.8°C and the climbs are comfortable.
2. Beach days at Cascais or Costa da Caparica: July and August, the only months that are both hot and reliably dry.
3. Warmth without the crowds: June, at 26.1°C and 14.1 mm, before the northern European school holidays begin.
4. Lowest prices: December to February, when mean highs still reach 15-16°C but rainfall runs above 100 mm a month.
5. Festivals: mid-June, when the Santo António street parties take over Alfama and Graça for several nights.
6. Photography without haze or crowds: late September, with 19.5 warm days and the light already lengthening.

What the calendar does to prices and crowds

Lisbon’s price curve has shifted over the past decade as the city has become a year-round destination, but the shape still follows the school holidays of northern Europe rather than the Portuguese weather.

1. July and August are peak for both rooms and flights, and the historic-centre districts are at their densest.
2. Mid-June fills the Alfama and Graça for the Santo António nights even though it is otherwise a shoulder month.
3. September holds close to August prices in the first fortnight, then drops noticeably in the last week.
4. The cheapest stretch is mid-January to the end of February, which is also the coldest and among the wettest.
5. Easter week moves between late March and late April and prices like a summer week wherever it lands.

The single cheapest good-weather week of the Lisbon year is usually the last week of September, after the prices drop but before the October rain arrives.