🇵🇹 Porto Climate Health Index
Monday, 21 September 2026 · updated 15:30 UTC · refreshes live through the day · LIVE
Modelled estimates · Medically reviewed guidance · Not an official warning service
est. = index derived by Mobi Doctor's model from the weather inputs. All values are modelled estimates from European weather and atmospheric forecast systems (Open-Meteo · CAMS/Copernicus) — not direct readings from a monitoring station in this city, and not official public-health warnings.
Cancer Immunology Researcher
The Climate Health Score for Porto today is 5.6/10 — high exposure on a 0–10 scale where 10 is extreme. It reflects the worst of ten live hazard readings for Porto — heat, UV, air quality, pollen, hydration demand, allergy, mosquito activity, fire weather, flu season and cold — and is recalculated through the day by Mobi Doctor's European Climate Health Index.
How heat behaves in Porto
Porto's northern Atlantic position keeps most summers gentle, which is precisely its vulnerability: rare sharp heatwaves arrive on a population and housing stock with little acclimatisation or cooling. Risk here concentrates almost entirely in a handful of spike days.
Porto is a granite city built against Atlantic damp: thick-walled, north-facing, made to hold warmth in. That inheritance turns rare heatwaves inside out — the housing stores exactly what the weather delivers, and its dense, ageing riverside parishes have some of Portugal's oldest populations in buildings without cooling. The Douro gorge adds its own twist: the river-level quays regularly run hotter and stiller than the breezier ridge of the upper town.
Heat and your health in Porto today
Feels-like maximum 33°C (air temperature 33°C) · tonight's minimum 18°C · humidity 28% · heat pillar score 5.6/10
Where today sits in Porto's year: the heat season here typically runs July to August, moderate — risk concentrates in rare spike episodes, peaking late July to mid-August. Tropical nights in Porto: rare — an exceptional-heatwave phenomenon rather than a seasonal pattern.
Heat stresses the body long before heatstroke. As the air temperature and humidity climb, your heart works harder to push blood to the skin for cooling, you lose fluid and electrolytes through sweat, and blood pressure can dip when you stand. That is why hot days bring more dizziness, fainting, migraines, kidney strain and falls — and studies of heatwave hospital admissions also report more urinary tract infections, thought to be linked to dehydration — not just classic heat exhaustion.
Night temperature matters as much as the daytime peak. When a night stays above 20°C — a tropical night — the cardiovascular system gets far less of its overnight recovery window — one reason heatwave mortality tracks hot nights more closely than hot afternoons. Tonight in Porto drops to around 18°C, which gives the body a proper recovery window.
Pollen count in Porto today
Pollen levels are currently minimal · score 0.1/10
Porto's pollen calendar: Grass April–June · olive May–June · plane and birch traces in spring. The live counts above show where today falls in that cycle.
Pollen allergy (hay fever) is triggered by different plants through the year: trees like birch and alder in spring, grasses in early summer, and weeds such as mugwort and ragweed from late July into autumn. Symptoms — sneezing, itchy eyes, a blocked nose, worsened asthma — flare when daily counts cross species-specific thresholds, and air pollution makes the same pollen load feel worse by priming the airways.
On high-count days: keep windows closed in the early morning and evening, shower and change after time outdoors, and start antihistamines before symptoms peak rather than after. If you use an asthma inhaler, keep it with you on high pollen days.
Allergy load in Porto today: pollen × air quality
Combined pollen-and-air allergy load 1.5/10 — pollen 0.1 amplified by air quality (EAQI 60) · estimated from live data
Porto's plane trees line dense granite streets where traffic idles, pairing spring pollen with the exhaust that primes airways; grass follows on the Atlantic wind. Humid air keeps loads moderate but persistent through the season.
Allergy risk is more than the pollen count. Exhaust particles damage the airway lining and prime the immune response, so the same grains provoke stronger symptoms on polluted days — and pollutant-stressed plants release more allergenic protein per grain. This combined score therefore reads pollen and air quality together: identical counts can feel very different on clean and dirty days, which is why it is tracked as its own pillar rather than folded into either input.
Today the combination is modest — sensitised people can treat this as a normal day, with the usual seasonal routine.
UV index in Porto today
Maximum UV index 6.0 · high on the WHO scale
Porto's strong-UV season: May to September — midday index 8–9 under clear skies.
UV radiation peaks between late morning and mid-afternoon and is invisible — it burns on cool, cloudy days too. At UV 8 and above, unprotected fair skin can burn in under 30 minutes. Repeated burns drive most skin-cancer risk, and some common medicines (certain antibiotics, diuretics, acne treatments) make skin dramatically more sun-sensitive.
Today: SPF 30–50 on exposed skin, sunglasses, and shade between 11:00 and 16:00. Reapply sunscreen every two hours outdoors.
Air quality in Porto today
European AQI 60 · poor (EAQI scale: 0 good → 100+ worst) · PM2.5 10.8 µg/m³ · ozone 120 µg/m³ · score 5.5/10
Porto's air is Atlantic-cleaned most of the year; winter evenings add wood-smoke particles across the metro area, and rare summer heat episodes bring the region's only meaningful ozone days.
Fine particles (PM2.5) reach deep into the lungs and bloodstream; ozone forms in sunny, hot weather and irritates the airways — which is why heatwaves and smog often arrive together. People with asthma, COPD, heart disease, pregnant women and children feel the effects first: more wheeze, more inhaler use, more chest tightness.
Today: sensitive groups should limit prolonged outdoor exertion, keep reliever inhalers to hand, and prefer mornings for exercise when ozone is lowest.
Fire weather around Porto today
Fire-weather score 8.2/10 — 33°C, 28% humidity, wind to 13 km/h · estimated (weather conduciveness, not active fires)
The hills of northern and central Portugal burn severely in bad years — October 2017 dropped ash on the city itself — and the Douro's terraced backcountry dries fast in heat. The score signals that regional readiness; city smoke days follow the interior's fires.
This pillar scores how conducive the weather is to wildfire — heat, dry air and wind, the published Angström approach — not actual fires. Its health meaning is smoke: wildfire smoke is concentrated fine particulate that can travel hundreds of kilometres, and a smoke episode hits the same people hardest as any pollution spike — asthma, COPD, heart disease, pregnancy, young children and older adults.
Conditions are fire-conducive today. If smoke does arrive: move indoors, close windows, skip outdoor exertion, and use an FFP2 mask if you must be out in visible haze. For fire itself, follow civil-protection instructions — this score is weather context, never an evacuation signal.
Hydration in Porto today
Hydration demand score 4.2/10 · estimated from live weather
Porto's cool damp norm builds no drinking habit — which is the trap when a spike arrives: on the few genuinely hot days, residents and visitors alike run hours behind their losses simply because nothing here ever taught them to pre-drink.
Fluid needs are not fixed — they scale with heat, humidity, dry air, UV and activity. Thirst lags behind need, especially in older adults, whose thirst signal weakens with age. Dark urine, headache, and light-headedness on standing are earlier and more reliable signals.
Today's guidance: Raised — drink small amounts often, without waiting for thirst; add extra for every hour outdoors or active. (Any fluid limit set by your doctor still applies.)
Mosquito activity in Porto tonight
Mosquito activity score 4.0/10 — tonight around 18°C at 28% humidity · estimated from live weather (activity, not disease risk)
Mosquito season in Porto: June to September, light dusk nuisance. The score above places tonight inside that season using live temperature and humidity.
Mosquitoes fly when nights are warm and humid enough — activity climbs steeply once evenings hold above about 15°C and peaks on still, muggy nights. Southern Europe adds the tiger mosquito, a day-biter now established across much of the Mediterranean, whose continued spread north ECDC tracks. In parts of southern and central Europe, late summer also brings limited local transmission of mosquito-borne infections such as West Nile virus — an activity score is not a disease-risk score, but high-activity weeks are when precautions earn their keep.
Practical: use a repellent containing DEET or icaridin at dusk, cover ankles and wrists outdoors in the evening, screen or close windows at night, and empty standing water on balconies weekly. Speak to a doctor about any fever that develops in the week after heavy bite exposure in an affected region.
Flu season in Porto: where today sits
Flu-season level 0.9/10 · seasonal climatology (ECDC winter pattern), not live case counts
Flu reaches Porto with the December rains and peaks in January, working through a compact city that spends winter indoors. Summer sits at the floor. The campaign from October is the local rhythm, and damp winter housing makes the respiratory season heavier here.
Influenza in Europe is sharply seasonal: transmission runs low through summer, builds from late autumn as life moves indoors and cool, dry air favours the virus, then peaks between December and February in ECDC's surveillance pattern. This pillar follows that climatology — it tells you where the calendar sits, not this week's case counts, and we label it that way rather than dress a seasonal curve up as live surveillance.
What to do with it: the score rising through autumn is the cue that vaccination time has arrived — October to November gives antibodies time to build before the peak, and matters most for over-65s, pregnant women, young children and anyone with heart, lung, kidney or immune conditions. At today's low seasonal level, a summer fever is far more likely to be something other than flu — and worth a doctor's opinion if it lasts.
Cold stress in Porto: the other end of the index
Cold-stress score 0.0/10 — tonight's minimum around 18°C
Porto's winter is Atlantic — 5–8°C, wet, rarely freezing — but granite housing with minimal heating holds a penetrating damp chill, the same indoor-cold pattern that drives Portugal's high winter excess mortality. Outdoor frost is uncommon; indoor cold is the local hazard.
Across Europe, cold claims more lives each year than heat — mostly quietly, through winter's extra heart attacks, strokes and respiratory infections rather than hypothermia. Cold air raises blood pressure and thickens blood within minutes, narrows airways, and stresses hearts hardest in the first snaps of the season, before bodies and habits adjust. Indoor cold in poorly heated homes does as much damage as the weather outside.
Cold is not a factor today — the score sits low, and this pillar will matter again when the season turns. It stays on the page year-round because an honest index needs both ends of the thermometer.
The Porto climate-health year
The Porto year is mostly gentle — grey, mild, damp-edged — with a grass and olive pollen season from April to June and a summer that usually peaks in the high 20s. Its medical significance concentrates in the exceptional: every few summers an Iberian heat dome pushes past the maritime defence and delivers 38–40°C to a city with near-zero acclimatisation, minimal air conditioning and no cultural heat routine. Those short episodes carry most of the city's annual heat risk.
| Season | Typical pattern in Porto |
|---|---|
| Heat season | July to August, moderate — risk concentrates in rare spike episodes |
| Peak heat | late July to mid-August |
| Tropical nights | Rare — an exceptional-heatwave phenomenon rather than a seasonal pattern |
| Pollen calendar | Grass April–June · olive May–June · plane and birch traces in spring |
| Mosquito season | June to September, light dusk nuisance |
| Strong-UV months | May to September — midday index 8–9 under clear skies |
Typical seasonal patterns from established climatology — the live scores above always reflect today's actual conditions.
Visiting Porto? What travellers should know
Porto's compact centre invites accidental exertion: the descent to the Ribeira is easy, the climb back is 60 metres of stairs in whatever heat the day holds, and the Dom Luís I upper deck is fully exposed steel. On hot days copy the local pattern — mornings on foot, afternoons in cellars and museums (the port lodges hold cellar temperatures year-round), evenings back outside. Remember the Douro valley day trip runs five to ten degrees hotter than the coast; Pinhão in July is a different climate from Porto.
If you do get ill away from home, you don't have to navigate a foreign health system for something a consultation can solve: speak to a Mobi Doctor physician online from your hotel or apartment.
Medicines that need extra care in Porto at 33°C
Most medicines are licensed for storage below 25°C; several everyday ones degrade fast beyond that — and a parked car at 33°C outside reaches roughly 49°C inside within half an hour. Today crosses those thresholds, so the following deserve attention.
Insulin all types & pens
Storage: Unopened: fridge 2–8 °C, never frozen. In-use pens: up to 28 days below 30 °C, away from sun.
In this heat: Heat above the labelled range can damage insulin, and warm weather can speed absorption from the injection site in some people, raising hypo risk — check glucose more often and follow the storage instructions for your specific product.
Hot car: A parked car can exceed 50 °C — insulin left inside should be replaced. Appearance is not a reliable damage test (some insulins are normally clear, some normally cloudy): if in doubt, ask a pharmacist.
GLP-1 injections Ozempic · Wegovy · Mounjaro
Storage: Unopened: fridge 2–8 °C. In-use: below 30 °C for a limited window — typically 3–6 weeks, check your leaflet.
In this heat: Above 30 °C the peptide degrades; do not use if the solution has particles or colour.
Hot car: Left in a hot car once — assume compromised and call a pharmacist before injecting again.
Adrenaline auto-injectors EpiPen · Jext · Emerade
Storage: Room temperature 15–25 °C. Never refrigerate — cold can jam the mechanism.
In this heat: Heat degrades adrenaline; a weakened pen may fail during anaphylaxis — check the viewing window stays clear.
Hot car: Glovebox reaches 60 °C+. A pen exposed even once should be replaced promptly.
Testosterone gels · injections · patches
Storage: Below 25–30 °C depending on product; gels are alcohol-based and flammable.
In this heat: Heat degrades gels; skin patches release MORE hormone when hot — absorption shifts on hot days.
Hot car: Do not store in vehicles; vials and gels lose potency within days of heat cycling.
Refrigerated antibiotics & biologics reconstituted suspensions · adalimumab…
Storage: Strict 2–8 °C cold chain. Reconstituted antibiotic syrups usually last only 7–14 days even refrigerated.
In this heat: Warm exposure silently cuts potency — the course may fail without looking any different.
Hot car: Never. A pharmacy-to-fridge trip in a hot car already needs a cool bag.
Thyroid & hormone tablets levothyroxine · HRT
Storage: Below 25 °C, dry, in the original blister.
In this heat: Repeated heat cycling (bathroom, car, windowsill) degrades levothyroxine measurably.
Hot car: Days of car storage can leave tablets under-dosed.
Medicines that change how your body handles heat
- Diuretics — amplify fluid and electrolyte loss — dizziness and falls risk climbs in heat
- Blood-pressure medicines (ACE-i, ARBs, beta-blockers) — can affect fluid balance, blood pressure and heat responses in some people — never stop or change them in hot weather without medical advice
- Lithium — dehydration concentrates blood levels toward toxicity — hydration is critical
- Antipsychotics, anticholinergics, some antidepressants — impair sweating and temperature regulation
- Insulin & sulfonylureas — faster absorption and reduced appetite in heat raise hypo risk
- NSAIDs (ibuprofen, naproxen) — strain the kidneys when dehydrated
- Stimulants (ADHD medicines) — raise core temperature during exertion
Never stop a prescribed medicine because of hot weather — a doctor can adjust timing or dose. Mobi Doctor's physicians can advise online, usually within minutes.
Should I speak to a doctor about heat symptoms?
Heat illness escalates in stages, and the right response depends on which stage you're seeing. Use these three tiers:
ACall 112 now — emergency signs
- Confusion, slurred speech, or disorientation; a seizure; or fainting that doesn't resolve within a minute or two
- Skin that has turned hot and dry after earlier heavy sweating, or a body temperature of 40 °C or more — signs of heatstroke
- Chest pain, severe shortness of breath, or a racing pulse that doesn't settle with rest in the cool
- Heat-exhaustion symptoms — dizziness, headache, nausea, cramps, pale clammy skin — that are no better after 30 minutes of rest, cooling and fluids: this can be heatstroke developing
- A baby, elderly person, or someone with heart disease who becomes limp, unresponsive, or "not themselves" in the heat
While waiting: move them to the coolest place available, remove excess clothing, cool the skin with water and moving air, and do not give fluids to anyone who is drowsy or confused.
BSpeak to a doctor today
- Heat symptoms that improve with cooling but keep returning on hot days, or leave you washed out for more than a day
- Repeated vomiting, or very dark urine / almost no urination through the day
- You take diuretics, blood-pressure, heart, or diabetes medication and feel unwell in the heat — some of these medicines change how your body handles fluid and temperature
- You are pregnant, or you have a heart or kidney condition that feels worse than usual in this weather
CSelf-care and recheck in 30 minutes
- Mild headache, tiredness, or thirst: move somewhere cool, remove unnecessary clothing, drink plenty of water or an isotonic sports drink, and cool the skin — spray or sponge with cool water and fan
- Recheck at 30 minutes. Improving means continue resting out of the heat for the rest of the day. Not improving is an emergency — call 112 (tier A), not a wait-and-see
Local numbers in Portugal: 112 — EU-wide emergencies · SNS 24 — 808 24 24 24 · for non-urgent concerns, a Mobi Doctor physician is online in minutes.
General guidance, not a personal assessment — when in doubt, call. In an emergency always call 112.
Sources for the medical guidance
The clinical guidance on this page follows public authority sources:
Medication storage limits follow each product's manufacturer information (SmPC / patient leaflet) — always defer to the leaflet for your specific product, and to your prescriber for personal advice.
Frequently asked questions
Is it safe to exercise outdoors in Porto today?
With care. The best window is tomorrow 07:00–09:00 — feels like ~17°. Cut intensity, drink before and after, and stop if you feel dizzy or stop sweating.
Do I need to worry about storing insulin or Ozempic in Porto this week?
Yes. Daytime highs around 33°C exceed the below-30°C limit for in-use pens if they are left in sun, bags or vehicles. Keep unopened stock in the fridge (2–8°C), carry in-use pens in an insulated pouch, and never leave them in a parked car.
Who is most at risk from today's conditions in Porto?
Today's Climate Health Score is 5.6/10 (High). Elderly: high · Children: high · Outdoor workers: high · Athletes: high. Driven by warm 33° conditions and extreme fire weather.
Will tonight be a tropical night in Porto?
No — tonight drops to around 18°C, below the 20°C tropical-night threshold, giving the body a proper recovery window.
When is the heat season in Porto?
Typically July to August, moderate — risk concentrates in rare spike episodes, peaking late July to mid-August. Rare — an exceptional-heatwave phenomenon rather than a seasonal pattern. Today's score at the top of this page reflects live conditions, not the seasonal average.
When is pollen season in Porto?
Grass April–June · olive May–June · plane and birch traces in spring. This page tracks live counts for six species (alder, birch, grass, mugwort, olive and ragweed) and updates them through the day.
When is mosquito season in Porto?
June to September, light dusk nuisance. The live mosquito-activity score on this page places tonight inside that season using temperature and humidity — it measures activity conditions, not disease risk.
Highest-risk cities in Europe today
All cities:
Porto score history — last 30 days
One point per day, refreshed by the daily rebuild. Full archive downloads in the press room.
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