Portugal in September: Weather, Crowds and the 64°F Sea, Region by Region

PORTUGAL · SEPTEMBER · REGION BY REGION

Portugal’s year turns in the first week of September, not on the calendar’s first day. European schools reopen, the campervans thin out on the Algarve’s coast road, and the weather stays roughly where August left it: 76°F afternoons in Lisbon and Faro, four rainy days in the capital across the whole month, three in the south. Up in the Douro, meanwhile, the first grapes are already going into the presses.

Add it up and you get summer’s numbers with about a quarter of summer’s crowd, which is why our twelve-month verdict files September under Best. What the month refuses to do is behave identically from the Minho to the Ria Formosa. This page sorts it region by region, weighs the three cities against each other, and says which corner of the country a swim-first week belongs in.

See the full 12-month verdict →

On this page

• Swimming, with three rain days all monthThe Algarve
• The harvest, from the first pickPorto & the Douro
• 76°F city days and 8pm sunsetsLisbon & the center
• Cork oaks, wine towns, a rental carThe Alentejo
• Lisbon, Faro and Porto comparedThe September table

Where to go in Portugal in September: Lisbon, the Algarve, the Douro and the Alentejo

Lisbon & the center: 76°F days, four rain days a month

Lisbon runs 76°F by day and 64°F at night in September, with 29 mm of rain spread across about four days. That is a dry month by almost any American standard, and it means the classic hill circuit, Alfama up to the castle and back down through Baixa, is a question of hydration rather than luck. Sunset sits at 8:07pm on the 1st and 7:22pm on the 30th, so the last week starts pushing dinner earlier. The city guide takes it from there.

Verdict: Best · Days: 76°F · Rain: 4 days · 29 mm · For: first-timers, Sintra day trips, food weeks

The Algarve: 3 rain days, 19 mm, and the crowd going home

Three rainy days. Nineteen millimetres for the entire month. The Algarve owns the driest column on our table, and it comes with 66°F nights, which is the difference between sleeping with the window open and negotiating with the air conditioning. Northern Europe goes back to school in the first week, so from the second week onward the beaches run at something closer to half speed while the water is at its warmest of the year so far. Which coast you choose matters more than the month: east versus west.

Verdict: Best · Rain: 3 days · 19 mm · Sea: 64°F and rising · For: beach weeks, families, late-summer swimmers

Porto, the Douro & the North: the vindimas open

Porto keeps 75°F afternoons but drops to 60°F at night, and pays for its Atlantic position with six rainy days and 64 mm, roughly double Lisbon’s rainfall. Nobody would call that wet. It does mean the north is where a September week benefits from an indoor bench: a Gaia cellar, a market lunch, a museum afternoon on the one day the sky closes in. Upriver, picking has begun on the terraces, and the quintas that take visitors are at their busiest. Windows, bookings and what a picking day involves sit in our harvest guide.

Verdict: Best · Rain: 6 days · 64 mm · Nights: 60°F · For: wine trips, river valleys

The Alentejo: inland heat early, walking weather late

No reference station of ours sits on the plains, so read Lisbon’s line and add a few degrees of inland heat (est.). Early September still cooks at midday out there. The last ten days are when the walking gets good and the light goes long over the stubble. What the region really has this month is timing: cork oaks over cut fields, wine towns pouring before the October visitors arrive, and empty roads between Évora and Monsaraz. Renting the car has its own rulebook here, worth reading before you land.

Verdict: Good early, better late · For: road trips, wine towns, dark skies

September weather in Portugal: temperatures city by city

30-year averages (1991–2020) for the three reference cities. Sea temperature is carried as one national Atlantic figure this month, 64°F, still climbing toward the south coast’s early-autumn crest. National crowds run at about 74% of the August maximum.

For a one-week trip, four rain days a month in Lisbon works out to roughly one showery afternoon, and even that tends to pass through. The nights are the packing question instead: 60°F in Porto after a 75°F afternoon catches people who packed only for the beach. The packing list covers the layer nobody brings.

September in Portugal: the vindimas, 64°F water and 8pm sunsets

The harvest opens. September starts the vindimas rather than closing them: pickers on the terraces at first light, the first musts fermenting, estates in the Douro and the Alentejo taking visitors who booked ahead. It is the thing a September trip has that a June one does not, and it changes what a day in wine country feels like. Dates, visits and the practical side belong to our harvest guide.

The water. 64°F is the Atlantic’s September reference here, roughly New England in high summer rather than the Gulf of Mexico, and it is still on the way up: the crest arrives in early autumn, which is where next month’s page tracks it. Anyone raised on the Jersey Shore will walk straight in. Anyone expecting bathwater should aim the beach days at the sheltered south rather than the exposed coast west of Lisbon.

The evenings. Sunset slides from 8:07pm on September 1 to 7:22pm on the 30th, forty-five minutes gone in four weeks. Early in the month a seven o’clock swim is still a daylight swim. By the last week, dinner at nine happens under café lights. That drift is the first clear sign that Portugal’s summer is a season and not a permanent setting.

Portugal in August, October or May instead

The last word

September is the month Portugal keeps its summer and hands back its space. Put the beach half of the trip in the second or third week, once the school exodus is complete and the Algarve’s 76°F days arrive with three rainy days in the whole month. Save the Douro for the end of it, when the presses are running. And pack the sweater for Porto’s 60°F nights, because a country that reads 75°F at four o’clock does not stay there at ten.

Compare the whole year in the twelve-month verdict, price the week with what Portugal costs, or build the route from the seven-day itinerary. The paperwork side hasn’t moved for US passports: check it once on entry requirements and forget it.