Hydration in the local climate: how much and what to drink

Lisbon hit 37°C on the afternoon of July 1st, and the Serviço Nacional de Saúde issued a heat advisory covering the entire Área Metropolitana de Lisboa for the third consecutive week. Health officials are urging residents to drink at least 1.5 to 2 litres of water daily — and considerably more if they are spending time outdoors or exercising. The warning comes as emergency departments at Hospital de Santa Maria reported a notable uptick in presentations linked to dehydration and heat exhaustion through June.

The timing matters. July and August consistently bring the most punishing heat to the Baixa and Alfama districts, where narrow streets trap warm air and foot traffic is relentless. Tourists compound the problem: many arrive from cooler Northern European climates and underestimate how quickly the Atlantic-influenced but fiercely dry Lisbon summer strips moisture from the body. The Instituto Português do Mar e da Atmosfera forecasts average July highs of 33°C this year, running roughly 2°C above the 30-year seasonal mean.

Local institutions are adapting. The Câmara Municipal de Lisboa expanded its network of public drinking fountains under the Bebedouros program — free, refillable stations now dot high-footfall zones from Praça do Comércio up through the Chiado and into Mouraria. The initiative added 14 new fountains in 2025 alone, bringing the total across the city to just over 80. Meanwhile, the Mercado de Campo de Ourique has become a reference point for residents looking to hydrate smartly: vendors there have seen demand for fresh gazpacho, água de coco, and cold-pressed juices surge by roughly 30 percent since May, according to the market's own trading figures.

What actually works — and what doesn't

Water remains the baseline. Nutritionists affiliated with the Faculdade de Ciências da Nutrição e Alimentação recommend plain water as the primary vehicle for hydration, supplemented by water-rich foods. Cucumber, watermelon, and tomatoes — all readily available at the Mercado da Ribeira on Avenida 24 de Julho — carry water content above 90 percent by weight and deliver small but meaningful electrolytes alongside their fluids.

Electrolytes are the part most Lisbon residents overlook. Sweat does not just carry water — it takes sodium, potassium and magnesium with it. Replacing fluids without replenishing those minerals can leave the body in a worse electrolyte imbalance than before. A pinch of sea salt in a large glass of water, a banana, or a small portion of unsalted nuts eaten alongside regular hydration can offset that loss without resorting to expensive sports drinks. A 500ml commercially branded isotonic drink runs between €1.80 and €2.50 at most Lisbon supermarkets; a banana at the Mercado de Arroios costs around €0.20 and does much the same job for most non-athletes.

Coffee and alcohol require honest accounting. Lisbon's café culture means the average resident drinks two to three bicas a day. Moderate caffeine intake at those levels does not cause net dehydration in habitual coffee drinkers, according to a 2024 review published in the European Journal of Nutrition — but alcohol, even a light imperial at a Bairro Alto esplanada, does accelerate fluid loss and should always be offset with an equal volume of water.

Building a practical daily routine

The most effective strategy is front-loading. Drinking 500ml of water before leaving home in the morning — ideally before the sun climbs past the Castelo de São Jorge and temperatures begin rising after 10am — gives the body a buffer before the day's heat accumulates. Carrying a reusable bottle and topping it up at one of the Bebedouros stations costs nothing and removes the temptation to skip a refill.

Anyone working outdoors on construction sites along the expanding Metro Transportes do Sul lines, cycling along the Ribeira waterfront, or simply walking the steep calçadas of Graça should aim for closer to 3 litres on days above 35°C. Children and adults over 65 are most vulnerable to rapid dehydration and should be monitored closely. Residents with specific health conditions, including kidney disease or heart failure, should speak with a médico de família before dramatically increasing fluid intake. The SNS 24 line — 808 24 24 24 — provides guidance around the clock for anyone uncertain about symptoms.