Lisbon’s summer weather brings a mix of warm days, bright skies, and those refreshing coastal breezes that shape daily life here. You’ll get long, dry, and sunny stretches with average highs around 28°C (82°F), and honestly, rain barely makes an appearance.
This balance of heat and ocean influence keeps summer in Lisbon lively and surprisingly comfortable, especially compared to some of those scorching inland spots.
July and August crank up the heat the most, while June and early September feel a bit milder but still plenty warm for outdoor plans. Sunshine hangs around for hours each day, and the UV index runs high, so you’ll want to keep sunscreen and shade handy.
The Atlantic nearby keeps sea temperatures lower than you might expect, which is actually a nice contrast when you leave the sunbaked streets for the beach. This blend of weather patterns lets you enjoy Lisbon’s outdoor cafés, coastline, and old neighborhoods all season long.
Overview of Lisbon’s Summer Climate
Lisbon’s summers deliver long hours of sunshine, warm but rarely extreme heat, and almost no rain. The city sits along the Atlantic, so temperatures stay more moderate than in Portugal’s interior, and steady ocean winds help keep things balanced.
Climate Classification
Lisbon fits into the Mediterranean hot-summer climate (Csa), at least according to the Köppen system. So, you’re looking at dry, sunny summers and mild, wetter winters.
During summer, daytime highs usually sit between 26°C and 30°C (79°F–86°F). Nights cool off, often landing around 18°C (64°F), so evenings feel a lot more pleasant. July and August barely see any rain, with totals often below 10 mm for the month.
Humidity generally stays moderate, and the Atlantic breeze keeps the air from feeling sticky. Sunshine averages about 10–11 hours per day, and the UV index climbs high, often hitting 8 or 9. You’ll definitely need sun protection if you’re outside much.
Summer Season Months
Summer in Lisbon runs from June through August. June kicks off the real warmth, with highs near 26°C (79°F) and little rain to worry about.
By July, temperatures hit their peak, averaging 28°C (82°F), and you’ll notice it’s the driest stretch of the year.
August keeps up the heat, often reaching 30°C (86°F) on the hottest days. Evenings cool down, which is a relief after a hot afternoon. The sea temperature rises too, ranging from 18°C to 20°C (64°F–68°F), making swimming doable, though it’s still chillier than the Mediterranean.
Daylight stretches to nearly 15 hours in June and slowly shrinks as summer goes on. This extra daylight is a big draw for visitors, giving you more time for outdoor adventures or just wandering the city.
Comparison With Other Regions in Portugal
Compared to Portugal’s interior, Lisbon’s summer weather feels milder and less intense. Cities like Évora or Beja in the Alentejo region often bake above 35°C (95°F), while Lisbon stays a few degrees cooler, thanks to the Atlantic.
Down in the Algarve, summer temperatures look similar to Lisbon’s, but the sea is warmer, averaging 21°C–23°C (70°F–73°F). Up north, places like Porto stay cooler and wetter, with more clouds and the odd summer shower.
So, if you want steady sunshine and warm but manageable heat, Lisbon really strikes a nice balance between the blazing interior and the damp, cooler north.
Typical Summer Temperatures in Lisbon
Lisbon’s summer climate means warm days, cooler evenings, and almost no rain. Temperatures stay pretty steady through the season, with just slight shifts between June, July, and August.
Average High and Low Temperatures
Historical data shows Lisbon’s average summer highs usually land between 26°C and 30°C (79°F to 86°F). The hottest stretch typically falls in late July and early August, when highs often nudge past 30°C (86°F).
Average lows are much milder, hanging around 17°C to 19°C (63°F to 66°F). These cooler nights help balance out the daytime heat, making Lisbon more comfortable than Portugal’s interior.
Humidity stays moderate, and the Atlantic breeze keeps the heat from feeling suffocating. This combo makes outdoor plans doable, even when it’s hot.
Daytime vs Nighttime Temperatures
During the day, Lisbon’s summer temperatures climb fast after sunrise, often hitting 25°C (77°F) by late morning. By mid-afternoon, highs usually peak between 28°C and 30°C (82°F to 86°F).
At night, the city cools off noticeably. Temperatures drop into the upper teens Celsius (mid-60s Fahrenheit), so you can sleep comfortably without cranking the AC.
If you stick close to the coast, you’ll notice evenings feel cooler than in the city’s inland neighborhoods. The Tagus River and Atlantic Ocean both help keep nighttime temperatures down, giving the waterfront a fresher vibe.
Monthly Temperature Trends
Summer in Lisbon runs from June through August, with a clear warming trend early on and a slight cooling as summer wraps up.
- June: Highs around 26°C (79°F), lows near 17°C (63°F).
- July: The hottest month, with highs close to 28°C to 29°C (82°F to 84°F) and lows around 18°C (64°F).
- August: Nearly as warm as July, with highs at 28°C to 30°C (82°F to 86°F) and lows near 19°C (66°F).
These steady patterns, backed by years of climate records, make Lisbon’s summer weather pretty predictable for planning outdoor fun.
Rainfall and Humidity During Summer
Summer in Lisbon means barely any rain and relatively dry air compared to the rest of the year. You’ll get long runs of clear skies, but humidity can swing between day and night, which changes how comfortable it feels.
Average Rainfall by Month
Lisbon’s summer months—June, July, and August—are the driest of the year. Historical data shows a sharp drop in precipitation once summer arrives.
- June: about 16 mm (0.6 in) of rain
- July: about 4 mm (0.2 in) of rain
- August: about 6 mm (0.2 in) of rain
Rainfall is almost non-existent in July and August. Most days are bone dry, and if it does rain, it’s usually just a quick drizzle.
Compared to autumn and winter, when monthly totals often top 100 mm, summer rainfall is minimal. If you’re planning to be outdoors, this is the season you can count on for dry weather.
Humidity Levels
Humidity in Lisbon shifts depending on the time of day and how close you are to the coast. In summer, average relative humidity sits around 60–65%.
Daytime often feels dry, with levels sometimes dropping below 40%, especially during hot afternoons. At night, humidity creeps up, often passing 70%. This swing happens because of the Atlantic’s influence and cooler overnight air.
If you’re near the coast in places like Cascais or Sintra, you might notice it’s a bit more humid than in central Lisbon. Inland areas by the Tagus Estuary usually feel drier, especially when it’s hottest.
Frequency of Rainy Days
Rain barely shows up in summer, both in volume and frequency. Historical records say:
- June averages about 5 days with measurable rain.
- July and August average only 2 days each.
Even then, the rain is usually brief and light. Drizzle makes up most of the summer’s precipitation, so you’re pretty unlikely to get caught in a downpour.
This pattern makes summer the safest bet for outdoor sightseeing, beach days, and day trips. You can plan stuff without worrying about rain messing up your schedule.
Sunshine Hours and UV Index
Lisbon’s summer weather comes with long daylight hours, strong sun, and moderate to high UV index values. These conditions are great for outdoor activities, but you’ll want to pay attention to sun safety.
Average Daily Sunshine
During summer, you’ll see 10 to 11 hours of sunshine per day on average. July and August are the brightest, with mostly clear skies.
Even in June and September, sunshine sticks around, averaging 9 to 10 hours daily. This long daylight gives you plenty of time for sightseeing, beach trips, or just wandering around in the evening.
Lisbon actually ranks among Europe’s sunniest capitals. The Atlantic location helps cut down on persistent cloud cover during summer.
| Month | Average Sunshine Hours/Day |
|---|---|
| June | 9–10 |
| July | 11 |
| August | 11 |
| Sept. | 9–10 |
You’ll rarely lose a summer day to gray skies here.
UV Index Levels
The UV index in Lisbon reaches some of its highest points in summer. Midday values usually land between 6 and 9, which is considered high to very high.
At these levels, unprotected skin can burn fast—sometimes in under 20 minutes. The strongest UV hits between 11 a.m. and 4 p.m., right when the sun’s overhead.
Even if the temperature feels mild, UV exposure stays strong, especially near the coast where water and sand reflect sunlight and bump up the intensity.
Lisbon’s UV index beats most northern European cities, though it’s not quite desert-level. Still, you should treat it seriously when planning time outdoors.
Sun Protection Recommendations
To stay safe in Lisbon’s summer sun, you’ve got to take some basic precautions. Sunscreen with SPF 30 or higher is a must if you’re spending much time outside. Reapply every couple of hours, especially if you’re swimming or sweating.
Wear lightweight, long-sleeved shirts, a wide-brimmed hat, and UV-blocking sunglasses. These keep you covered and comfortable.
Try to plan outdoor stuff for the morning or late afternoon, when UV is lower. If you have to be out during peak hours, find shade whenever you can.
Kids and people with sensitive skin need extra care. Even short exposure without protection can lead to sunburn or worse. If you prep ahead, you can enjoy Lisbon’s summer without unnecessary risks.
Sea Temperatures and Coastal Conditions
The Atlantic Ocean shapes Lisbon’s summer with moderate sea temperatures, steady breezes, and shifting coastal winds. These factors affect how the water feels for swimming and how the shoreline changes from day to day.
Average Sea Temperature
Sea temperatures along Lisbon’s coast stay cooler than down south in the Algarve. The Atlantic keeps things refreshing, even in the hottest months.
From June to September, average sea temperature ranges between 18.5°C and 19.8°C (65°F–68°F). The warmest water usually shows up between late August and early October, sometimes just over 20°C (68°F).
For quick reference:
| Month | Avg. Temp (°C) | Swimming Comfort |
|---|---|---|
| June | 18.5 | Cool |
| July | 18.8 | Cool |
| August | 19.6 | Cool to mild |
| Sept. | 19.8 | Mild |
You’ll notice the water is cooler than in the Algarve, but it stays steady enough for swimming most of the summer.
Best Months for Swimming
If you want the warmest sea, plan your swims for late summer. August, September, and even early October offer the mildest water, usually right around 20°C.
Earlier in the season, like June or July, the ocean feels brisk. Plenty of people still take a dip, but you might not want to linger long.
Locals and surfers often use wetsuits, especially in early summer. By late August, the ocean feels a bit more welcoming for casual swimmers, though it never really matches Mediterranean warmth.
If you’re sensitive to cold water, September is your best bet. The sea holds onto summer heat, and the air stays warm, so you get a nice balance.
Coastal Breezes and Winds
Atlantic winds shape Lisbon’s shoreline, and they can cool the air even when it’s hot out. In summer, you’ll often notice a northwest breeze called the Nortada.
Locals rely on this wind to regulate Portugal’s weather, keeping coastal spots way more comfortable than the stuffy inland areas. These breezes sometimes make evenings feel chilly, especially close to the Tagus River or out on open beaches.
If you’re staying out after sunset, you’ll probably want a light jacket.
When it comes to water activities, wind strength really makes a difference. The Nortada can whip up choppier waves, which surfers and windsurfers seem to love.
Swimmers might notice the currents get stronger on windy afternoons. Mornings usually feel calmer, with gentler winds and smoother water.
If you’re after quiet, glassy sea, just head out earlier in the day.
Practical Tips for Experiencing Lisbon’s Summer Weather
Lisbon summers bring long sunny days, warm afternoons, and cooler evenings along the coast. You’ll probably enjoy things more if you’re ready for midday heat, Atlantic breezes, and that strong evening sun.
What to Pack
You’ll want lightweight clothing—think cotton shirts, shorts, and loose dresses. Toss in at least one long-sleeve layer or a light jacket for when the evenings get cool, especially if you’re hanging out by the Tagus or the ocean.
A wide-brimmed hat, sunglasses, and sunscreen are must-haves, honestly. Lisbon’s summer sun doesn’t mess around, and even when it’s breezy, those UV levels stay high.
If you’re planning to wander the city’s hills and cobblestones, bring sturdy shoes or sandals with a decent grip. Heading to beaches like Cascais or Costa da Caparica? Don’t forget a swimsuit and flip-flops.
A small daypack and a refillable water bottle will help you stay hydrated. You might want to throw in a compact umbrella too, just in case you get caught in one of those rare summer showers.
Staying Comfortable Outdoors
Afternoons get hot, with highs usually hitting 28–30°C (82–86°F). If you want to skip the heat, try sightseeing in the morning or late afternoon when it’s cooler and the light feels softer.
Find some shade in parks or tree-lined squares during midday. Locals often take a siesta-style break indoors between 1 p.m. and 4 p.m., which honestly sounds like the perfect excuse for a long lunch.
If you’re sensitive to heat, pick restaurants and cafés with outdoor seating under awnings or indoor spots with fans or AC. Coastal breezes help, but inland neighborhoods heat up fast.
Carry bottled water or refill at public fountains. Since Lisbon has those famous steep hills, take your time and rest when you need to, especially if you’re climbing up to a viewpoint like Miradouro da Senhora do Monte.
Weather-Related Travel Advice
Lisbon’s summer stays mostly dry. Still, you might catch a quick shower in June or early September.
July and August usually bring clear skies. Rain almost never shows up during those months.
Trams and buses fill up fast, especially when it’s hot out. If you want to dodge the worst crowds, try heading out earlier or waiting until the evening.
Metro stations tend to feel cooler than riding above ground. You’ll probably find them a bit more comfortable, honestly.
Thinking about a day trip to Sintra or Cascais? Those spots usually run a few degrees cooler, thanks to their altitude or the ocean breeze. Definitely toss a light layer in your bag for those trips.
Check the sunset time before you leave. In midsummer, the sun hangs around past 9 p.m., so you get more daylight for exploring, but keep in mind you’re exposed to UV rays for longer. Maybe pack some sunscreen if you’re out late?