🇭🇷 Zagreb Climate Health Index

Monday, 14 September 2026 · updated 03:30 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.

The Climate Health Score for Zagreb today is 3.8/10 — moderate exposure on a 0–10 scale where 10 is extreme. It reflects the worst of ten live hazard readings for Zagreb — 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 Zagreb

Zagreb's position between Medvednica and the Sava plain gives it continental heat spells with an appreciable urban heat island. Its summers are lengthening toward Pannonian patterns — more warm nights than its altitude and latitude once implied.

Zagreb leans against Medvednica with its back to the mountain's cool and its face to the Pannonian plain's heat: the Lower Town's Austro-Hungarian blocks and courtyards store the warm spells the plain delivers, while the Upper Town's ridge catches what breeze exists. The Sava's floodplain south of the rails — Novi Zagreb's slab estates — heats through concrete. Nights have warmed conspicuously: the city now runs more tropical nights than its altitude and latitude once implied.

Heat and your health in Zagreb today

Feels-like maximum 24°C (air temperature 23°C) · tonight's minimum 15°C · humidity 79% · heat pillar score 0.0/10

Where today sits in Zagreb's year: the heat season here typically runs June to early September, Pannonian spells, peaking mid-July to mid-August. Tropical nights in Zagreb: increasingly regular in the dense Lower Town during spells.

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 Zagreb drops to around 15°C, which gives the body a proper recovery window.

Pollen count in Zagreb today

Leading species: Mugwort at ~8 grains/m³ · pollen score 2.9/10

Zagreb's pollen calendar: Alder February–March · birch April · grass May–July · ragweed August–September, among Europe's strongest. 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 Zagreb today: pollen × air quality

Combined pollen-and-air allergy load 2.8/10 — pollen 2.9 amplified by air quality (EAQI 26) · estimated from live data

Zagreb sits in strong ragweed country — the Pannonian influence brings heavy August and September loads — on top of birch and grass seasons and the city's basin-edge traffic. Late summer, not spring, is Zagreb's allergy peak.

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 Zagreb today

Maximum UV index 4.7 · moderate on the WHO scale

Zagreb's strong-UV season: May to August — midday index 7–8.

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.

Sun protection is low-priority today, but sunscreen remains sensible for extended time outdoors.

Air quality in Zagreb today

European AQI 26 · fair (EAQI scale: 0 good → 100+ worst) · PM2.5 8.2 µg/m³ · ozone 67 µg/m³ · score 2.1/10

Zagreb's winter wood-and-coal particles are the notorious season; in summer the basin's hot stagnations build ozone instead, with the mountain storms doing the flushing the geography withholds.

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.

Levels are acceptable for outdoor activity today for most people, including sensitive groups.

Fire weather around Zagreb today

Fire-weather score 0.5/10 — 23°C, 79% humidity, wind to 20 km/h · estimated (weather conduciveness, not active fires)

Continental Croatia burns modestly — field and scrub fires in drought summers — while the serious fire country lies over the mountains on the coast. Zagreb's score reads local dryness; smoke exposure here is occasional and regional.

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 not notably fire-conducive today. If you see or smell smoke regardless, treat it like a pollution episode: head indoors, close the windows, and postpone outdoor exertion.

Hydration in Zagreb today

Hydration demand score 0.0/10 · estimated from live weather

Zagreb's continental spells sweat the Lower Town's grid hard by afternoon: the plain's dry-hot runs evaporate losses invisibly, and the coast-bound transit crowd habitually saves its water discipline for the beach it has not reached yet.

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: Normal — drink to thirst; keep water with you on long outings.

Mosquito activity in Zagreb tonight

Mosquito activity score 3.8/10 — tonight around 15°C at 79% humidity · estimated from live weather (activity, not disease risk)

Mosquito season in Zagreb: May to September, Sava floodplain dusk — a strong season. 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 Zagreb: where today sits

Flu-season level 0.9/10 · seasonal climatology (ECDC winter pattern), not live case counts

Flu in Zagreb runs December to February, peaking in January through tram-mixed winter crowds. Summer sits at the floor. The autumn campaign is the standing advice for seniors and chronic patients.

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 Zagreb: the other end of the index

Cold-stress score 0.0/10 — tonight's minimum around 15°C

Zagreb winter is continental: grey freezes, snow most years, -10°C in cold snaps off the Pannonian plain. Heating is universal. January outdoor cold is real and the pillar registers it — a different climate from coastal Croatia's mild winters.

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 Zagreb climate-health year

The Zagreb year runs continental with a Mediterranean lean: real winters, an alder-birch spring, grass to July — then ragweed, the Pannonian plague, loading August and September with some of Europe's highest counts outside Hungary. Summer spells park in the low-to-mid 30s with warm nights in the dense grid. Violent storms off the mountain reset the air. September grades into the region's stable autumn.

Typical seasonal patterns from established climatology — the live scores above always reflect today's actual conditions.

Visiting Zagreb? What travellers should know

Zagreb's centre works on the Vienna pattern at smaller scale: arcaded streets and courtyard cafés carry you through midday, the Upper Town suits mornings, and Maksimir's deep shade or the Sljeme cable car — 1,000 metres of instant cooling — solve afternoons. Jarun and Bundek lakes are where the city itself swims. Coast-bound visitors treating Zagreb as a transit stop should note the plain runs hotter than the islands they are heading to; the car's dashboard reading between here and the coast will be the trip's highest.

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 in Zagreb this week

Temperatures are currently inside normal storage ranges. Standard advice applies: keep medicines below 25°C, out of direct sun, and never in a parked vehicle.

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:

Local numbers in Croatia: 112 — EU-wide emergencies · 194 — ambulance · 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 Zagreb today?

Yes — heat is not a limiting factor today (heat score 0.0/10). Usual sun protection applies.

Do I need to worry about storing insulin or Ozempic in Zagreb this week?

Standard rules apply this week: unopened stock in the fridge at 2–8°C, in-use pens below 30°C away from direct sun.

Who is most at risk from today's conditions in Zagreb?

Today's Climate Health Score is 3.8/10 (Moderate). Elderly: low · Children: low · Outdoor workers: low · Athletes: low. No dominant environmental hazard today.

Will tonight be a tropical night in Zagreb?

No — tonight drops to around 15°C, below the 20°C tropical-night threshold, giving the body a proper recovery window.

When is the heat season in Zagreb?

Typically June to early September, Pannonian spells, peaking mid-July to mid-August. Increasingly regular in the dense Lower Town during spells. Today's score at the top of this page reflects live conditions, not the seasonal average.

When is pollen season in Zagreb?

Alder February–March · birch April · grass May–July · ragweed August–September, among Europe's strongest. 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 Zagreb?

May to September, Sava floodplain dusk — a strong season. 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:

Zagreb 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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Cite this page: “Mobi Doctor — European Climate Health Index, Zagreb Climate Health Index”, https://www.mobidoctor.eu/health-index/zagreb/ — updated daily, data CC-BY 4.0 with attribution.