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

The thermometer at Senate Square hit 28°C on Tuesday afternoon, and by early evening the queues at the Hakaniemi Market Hall's juice and smoothie stalls stretched past the entrance doors. It was the fourth consecutive day above 25°C in the capital — a stretch that, according to the Finnish Meteorological Institute, is statistically rare but increasingly common, with Helsinki now averaging roughly three such heat periods per summer compared to one per decade in the 1990s.

That shift matters because Finns are simply not acclimatised to sustained warmth. The body loses significantly more fluid through sweat in high humidity combined with heat, and the Baltic coastal air that blankets Helsinki in July tends to keep relative humidity above 70 percent on warm days. People drink far less than they should, largely because they do not feel thirsty until dehydration has already set in — a physiological lag that becomes more pronounced after the age of 50.

What Helsinki's wellness community is actually recommending

The Finnish Institute for Health and Welfare, known by its Finnish acronym THL, published updated hydration guidance in March 2026 that adjusts the long-standing two-litre-per-day baseline upward to 2.5 litres for adults during periods when the ambient temperature exceeds 25°C. That figure accounts for water obtained from food — roughly 700 to 800 millilitres on a typical Finnish diet rich in soups, berries and vegetables — meaning the actual drinking target sits closer to 1.7 litres of fluid on a hot day, rising to 2.2 litres during outdoor physical activity.

The Töölö Sports Hall on Paavo Nurmi Square has been distributing THL's updated guidance at the reception desk since June, and staff there report a noticeable uptick in questions about electrolytes. That is not a coincidence. When you sweat heavily, you lose sodium, potassium and magnesium alongside water, and replacing fluid alone without those minerals can leave people feeling sluggish and prone to cramping. Sports nutritionists at the Mehiläinen clinic network on Runeberginkatu 47 recommend adding a small pinch of sea salt and a squeeze of lemon to water during extended outdoor sessions — a low-cost alternative to commercial sports drinks, which in Finnish supermarkets retail for between €1.80 and €3.20 per 500ml bottle.

Plain tap water remains the gold standard and Helsinki's is exceptionally good. The Helen municipal water utility draws primarily from Lake Päijänne via a 120-kilometre tunnel, and independent testing in 2025 rated it among the five cleanest municipal supplies in Northern Europe. A litre costs the consumer approximately €0.001 at the tap. The café culture around Kallio and Punavuori neighbourhoods has begun normalising the practice of asking for tap water alongside coffee orders — a habit common in Stockholm and Amsterdam but historically rare in Helsinki.

What to drink, and what to avoid

Coffee deserves its complicated reputation. Finns consume an average of 4.1 cups per day according to 2024 statistics from the National Coffee Association of Finland — the highest per capita rate in the world — and the mild diuretic effect of caffeine has long prompted warnings about relying on coffee for hydration. The current consensus is more nuanced: moderate coffee consumption, meaning up to four cups daily, does not produce net fluid loss in habituated drinkers. The concern kicks in beyond that threshold, particularly when coffee replaces rather than accompanies water intake.

Alcohol dehydrates aggressively, and the long July evenings around Eiranranta and the Kaivopuisto beach area make cold beer feel like refreshment. It is not. Each standard drink increases urine output and suppresses the hormone that signals the kidneys to retain water. A practical rule from sports medicine: one glass of water per alcoholic drink, consumed before rather than after.

Berry-based drinks offer one genuinely Nordic advantage. Lingonberry and sea buckthorn juices, widely sold at the Hietalahti Market and most Prisma supermarkets, deliver potassium and vitamin C alongside fluid. Diluted one-to-one with water, they make a functional electrolyte drink at roughly €0.60 per 250ml serving. As summer heat in Helsinki grows harder to predict season by season, that kind of accessible, local solution may be worth keeping in the fridge. Consult a physician or registered dietitian at your local health centre — terveysasema — for personalised guidance.