Most cities can now predict a dangerously hot day. Far fewer can answer the next questions with confidence: which residents live in rooms that will not cool overnight, who will check an isolated older person, whether outdoor work will stop, how emergency departments will recognise the surge, and where someone can go without being required to buy anything.
The World Health Organization’s second-edition guidance on heat-health action plans, released in June 2026, is built around eight elements: governance, warning systems, identification of populations at increased risk, communication, health-system resilience, reducing exposure, surveillance, and evaluation. The list makes an important distinction. A meteorological alert describes a hazard. A heat-health plan changes what institutions do before, during and after it.
Heat is a distributed emergency
Floods and storms produce visible damage. Heat accumulates inside bedrooms, workplaces, buses, care homes and bodies. Death certificates may record cardiovascular, renal or respiratory causes rather than heat itself. The emergency is therefore easy to underestimate and difficult to manage through a single agency.
Health departments need meteorologists, housing authorities, labour inspectors, schools, emergency managers, utilities, transport providers and community organisations. A plan should name who convenes them, who can trigger actions and who remains accountable when thresholds are crossed.
Risk depends on exposure and capacity, not age alone
Older people, infants, pregnant women, people with chronic conditions, outdoor workers, athletes, tourists, migrants and people with limited resources can face higher risk. But categories are not enough. An older person in a shaded, ventilated home with support may be safer than a younger worker on a roof with no control over breaks.
Cities need local vulnerability mapping that combines temperature, housing, tree cover, health, social isolation and access to cooling. Privacy matters: a list of vulnerable residents can support outreach, but it must not become a poorly secured register of medical and social information.
Warnings must trigger specific decisions
Generic advice to drink water and stay cool places responsibility on individuals who may lack cool space, money or control over work. Tiered thresholds should activate concrete measures: extend pool or library hours, open cooling rooms, adjust school activities, suspend unsafe outdoor labour, check care facilities, increase ambulance readiness and protect electricity supply.
Messages should explain both day and night risk. When temperatures remain high overnight, the body loses recovery time and indoor spaces may become progressively hotter. Advice must be multilingual, accessible and distributed through channels beyond smartphones.
Cooling is housing and urban policy
Air conditioning can save lives, but universal reliance creates cost, power-demand and emissions problems and may fail during outages. WHO guidance emphasises reducing heat exposure through building design, retrofits, shade, green and blue infrastructure, and passive cooling suited to local climates.
Tenants need enforceable protection from dangerous indoor heat, not only suggestions to modify a property they do not own. New buildings should be assessed for summer performance as well as winter efficiency. Street trees require water, soil volume and maintenance; a ribbon-cutting does not create shade for the next heatwave.
Health systems need to see the signal early
Emergency departments, primary care, pharmacies and ambulance services can monitor heat-related symptoms and medication risks. Real-time or near-real-time surveillance helps identify affected neighbourhoods and evaluate whether interventions work. It also requires consistent definitions and rapid data sharing.
Preparedness includes staff safety. Health and care workers may be operating in overheated facilities while demand rises. Backup power, cooling zones, staffing plans and outreach protocols should be tested before summer.
Workplaces need enforceable heat rules
Outdoor workers and people in kitchens, warehouses, factories and delivery jobs cannot always follow public advice to avoid exertion. Heat risk depends on temperature, humidity, radiant heat, clothing, workload and acclimatisation. Employers need thresholds for water, shade, rest, scheduling and emergency response that fit the work rather than relying on workers to self-identify distress.
Piece rates and insecure contracts can discourage breaks even when a policy exists. Inspection and worker reporting channels therefore belong in a heat-health plan. Migrant workers need information in languages they understand and protection from retaliation.
The economic case is not opposed to health protection. Heat reduces concentration and productivity and increases mistakes. Planning work around dangerous conditions is a form of operational resilience, not an optional welfare programme.
Mass gatherings reveal the planning gap
Festivals, pilgrimages, elections and sporting events concentrate people in sun, crowds and unfamiliar places. WHO’s 2026 work on mass gatherings recommends event-specific risk assessment, escalation protocols, hydration, shade, medical capacity and communication. Organisers cannot assume attendees will self-regulate when tickets, travel and group pressure encourage them to stay.
Event permits can require heat plans tied to forecasts. Cancellation or schedule changes should be defined in advance, with authority and financial responsibility clear enough that safety decisions are not delayed by commercial negotiation.
Evaluation turns a plan into infrastructure
After each season, authorities should compare forecasts, interventions, health outcomes, service use and unequal impacts. Did cooling centres open where people could reach them? Did employers comply? Were messages understood? Which neighbourhoods experienced excess deaths or ambulance calls?
Heat plans should be funded and rehearsed like other emergency systems, while long-term urban changes reduce exposure year by year. The goal is not to produce a better warning graphic. It is to ensure that when the forecast turns red, the city already knows how to protect people who cannot simply step into a cool private room.
