🇬🇧 London Climate Health Index

Friday, 7 August 2026 · updated 10:33 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 London today is 4.0/10 — moderate exposure on a 0–10 scale where 10 is extreme. It reflects the worst of ten live hazard readings for London — 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 London

London's peaks look modest by southern standards, but its housing was engineered to retain heat: brick terraces and modern flats alike stay hot indoors long after the weather breaks, and air conditioning is rare. Since 40 °C fell for the first time in 2022, short extreme spikes on an unadapted city are the defining risk.

London's heat problem is indoors: nineteenth-century brick terraces and twenty-first-century glass flats alike were engineered to keep warmth in, air conditioning is rare at home and absent from most of the deep Tube, and the urban heat island keeps inner boroughs several degrees above the green belt at night. When 40°C arrived in 2022 the infrastructure — rails, power, housing — showed how narrow the margin is. Top-floor flat dwellers and older residents in south- and east-London terraces are most exposed.

Heat and your health in London today

Feels-like maximum 23°C (air temperature 25°C) · tonight's minimum 18°C · humidity 39% · heat pillar score 0.0/10

Where today sits in London's year: the heat season here typically runs mid-June to mid-August — short spikes on a mild baseline, peaking mid-July, spike days can exceed 35°C and have touched 40°C. Tropical nights in London: rare — inner-borough nights stay warm only during major spikes.

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 London drops to around 18°C, which gives the body a proper recovery window.

Pollen count in London today

Leading species: Mugwort at ~10 grains/m³ · pollen score 3.2/10

London's pollen calendar: Birch April · plane April–May · grass May–July, the UK's main allergy season. 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 London today: pollen × air quality

Combined pollen-and-air allergy load 3.0/10 — pollen 3.2 amplified by air quality (EAQI 24) · estimated from live data

London's plane trees — the avenue standard — flower into air where NO₂ still concentrates along canyon streets, and birch parks add April load. Grass, the UK's dominant allergy, carries June; pollution priming makes identical counts feel worse in zone one than in the suburbs.

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 London today

Maximum UV index 5.5 · moderate on the WHO scale

London's strong-UV season: May to August — midday index 6–7.

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 London today

European AQI 24 · fair (EAQI scale: 0 good → 100+ worst) · PM2.5 6.8 µg/m³ · ozone 60 µg/m³ · score 1.9/10

London's air issue is chronic rather than episodic: traffic NO2 in the canyons year-round, with ozone joining only on hot, still days — which is why a heat spike here usually shows up in the air line too.

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 London today

Fire-weather score 3.6/10 — 25°C, 39% humidity, wind to 12 km/h · estimated (weather conduciveness, not active fires)

The 40°C day of July 2022 turned London's dry grass margins into fire fronts — Wennington burned on live television — rewriting the assumption that wildfire is someone else's hazard. Drought summers now bring real grass-fire readiness, which is what the score reads.

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 London today

Hydration demand score 0.0/10 · estimated from live weather

London's spikes meet a city acclimatised to mild: the deep Tube adds a hidden sauna leg to every journey, few habits include carrying water, and brick flats keep losses running overnight — on 33°C days, drink on schedule, not on thirst.

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 London tonight

Mosquito activity score 3.7/10 — tonight around 18°C at 39% humidity · estimated from live weather (activity, not disease risk)

Mosquito season in London: June to August, a light nuisance 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 London: where today sits

Flu-season level 0.5/10 · seasonal climatology (ECDC winter pattern), not live case counts

London's flu wave builds through December and peaks in January, the Tube doing world-class mixing. Summer sits at the floor. The NHS autumn campaign from October covers over-65s, pregnant women, young children and chronic patients — the standing advice 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 London: the other end of the index

Cold-stress score 0.0/10 — tonight's minimum around 18°C

London winter is damp 2–8°C with occasional snaps, and the UK's excess winter mortality runs high for the climate — poorly insulated stock and fuel poverty, not Arctic air, are the mechanism. The pillar reads outdoor cold; the indoor kind is the documented burden.

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 London climate-health year

The London year is mild at both ends with a sharpened middle: birch pollen opens April, grass runs May to July (the UK's dominant allergy), and the heat risk concentrates in short spikes between mid-June and mid-August — two to five day episodes that now regularly cross 35°C. Because baseline summers stay moderate, acclimatisation is low and each spike lands hard. September cools quickly; winter is long, grey and damp rather than cold.

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

Visiting London? What travellers should know

London's heat trap is the Underground: the deep lines — Central and Bakerloo above all — run hotter than the street on spike days, so surface routes, riverboats and walking beat the Tube when temperatures climb. Museums are the free, cooled backbone of a hot-day itinerary. If you have booked a top-floor summer let, check for a fan before you need one — most housing has no cooling at all. The parks are the city's evening lung: join the after-work crowds on the grass rather than fighting the afternoon.

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 London 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 United Kingdom: 112 — EU-wide emergencies · NHS 111 — urgent medical advice · 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 London 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 London 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 London?

Today's Climate Health Score is 4.0/10 (Moderate). Elderly: low · Children: low · Outdoor workers: low · Athletes: low. Led by UV at moderate levels — no extreme single hazard today.

Will tonight be a tropical night in London?

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 London?

Typically mid-June to mid-August — short spikes on a mild baseline, peaking mid-July, spike days can exceed 35°C and have touched 40°C. Rare — inner-borough nights stay warm only during major spikes. Today's score at the top of this page reflects live conditions, not the seasonal average.

When is pollen season in London?

Birch April · plane April–May · grass May–July, the UK's main allergy season. 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 London?

June to August, a light nuisance 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:

London score history — last 30 days

One point per day, refreshed by the daily rebuild. Full archive downloads in the press room.

Embed this live London score

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