Prepare before temperatures peak
Check the Met Office forecast and Heat-Health Alerts rather than waiting until the home is already hot. Identify the coolest usable room, make sure curtains or blinds work, test fans, and understand which windows can be opened safely at night. The Met Office's extreme-heat advice specifically includes closing curtains in rooms that face the sun, drinking plenty of fluids and avoiding the strongest midday sun. If someone depends on powered medical equipment, keep their care plan and emergency contacts accessible.
UKHSA advises closing windows and curtains in rooms that face the sun, drinking plenty of fluids and checking people who may be at higher risk. Older people, babies, young children, pregnant women and people with some underlying health conditions may need extra support.
Manage the home through the day and night
Before direct sun reaches a window, deploy available shading and close the room off if it is not needed. Reduce oven use and other internal heat where practical. During the hottest part of the day, compare indoor and outdoor conditions before opening windows; ventilation helps most when the incoming air is cooler.
After outdoor temperatures fall, use safe cross-ventilation to release stored heat. Do not compromise security, child safety, fire escape or protection from outdoor pollution. A fan can improve comfort, but very hot conditions and health vulnerability require attention to official advice rather than reliance on one appliance.
If you use portable air conditioning
Set up the correct window kit before the hottest day. Route the exhaust outdoors, keep gaps small without creating an unsafe obstruction, and follow clearance, drainage and electrical instructions. Do not use an extension lead unless the manufacturer explicitly permits the arrangement.
Cool the occupied room rather than attempting to condition an open staircase or whole home with one portable unit. Keep doors closed where appropriate, choose a moderate set point and monitor the room used for sleep. Indoor noise may determine whether a unit is practical overnight.
Recognise when heat is a health emergency
Heat exhaustion can include tiredness, dizziness, headache, nausea, cramps, heavy sweating, thirst and weakness. Move the person to a cool place, cool their skin and follow current NHS or UKHSA advice. This article is general preparation information and is not a substitute for medical assessment.
Heatstroke is a medical emergency. UKHSA guidance explains when to call 999, including when a person remains unwell after cooling or shows serious symptoms such as confusion, very high temperature, seizure or loss of consciousness. Keep the official guidance bookmarked and check its latest wording during a heat event.
Prepare a room and equipment inventory
List the rooms used for sleep, work and care, then identify the coolest fallback space. Record orientation, floor level, shading, safe opening options and any equipment that adds heat. Check that blinds, latches, fans and approved portable-air-conditioner parts are present and serviceable before an alert. Keep rating labels and manuals accessible. Do not discover during the hottest evening that the exhaust panel cannot fit the window, the filter is blocked or the only usable socket would require an unsuitable extension lead.
Put practical supplies in the same plan: drinking water, suitable light bedding, medication and care instructions, charged communication devices and contact details for people who may need help. Review power-cut arrangements where powered medical equipment or lifts matter. The household plan should identify who checks whom and when. It should not publish private health information or assume that a connected device, automated alert or cooling appliance replaces direct contact with somebody at higher risk.
Operate one room deliberately
Concentrate limited cooling on the occupied room. Close internal doors where appropriate, deploy shading before direct sun and reduce avoidable heat from cooking, lighting and computers. If a portable unit is used, keep its approved exhaust short and well fitted, preserve the air clearances in the manual and manage condensate as instructed. A low thermostat setting does not make an undersized or leaking setup cool faster; it can instead extend compressor operation.
Compare indoor and outdoor conditions before changing ventilation. When outside is hotter, uncontrolled opening can add heat; when it becomes cooler, safe cross-ventilation can help remove stored heat. Account for noise, pollution, child safety, fire escape and ground-floor security. A top-floor flat or single-aspect room may need a different plan from a shaded house. Keep the action responsive to the actual room rather than repeating one national rule regardless of conditions.
Review the event before the next hot spell
After temperatures ease, record what happened: the forecast peak and overnight low, room readings, measures used, comfort or symptoms, equipment hours and any failure in the plan. Note whether the room released heat overnight and which intervention had a repeatable effect. Do not use one unusually mild night as proof that the building is fixed. A short factual record helps decide whether better shading, ventilation work, a different room arrangement or active cooling deserves attention before the next event.
Inspect portable equipment and window accessories after use, clean and store them according to the manual, and check for damage rather than putting a wet or faulty unit away. Update contact details, alert preferences and the room inventory. If a permanent installation is now being considered, use the evidence to brief installers on occupied rooms, simultaneous demand, sound sensitivity and permissions. An emergency purchase should not become the specification for a long-term system without a fresh design check.
Review the plan with every person who may need to use it, including anyone who provides care or visits the property during hot weather. Confirm which actions are safe for them to perform and which require help. Keep the official heat guidance link, local forecast route and emergency contacts visible without relying on a single app or account. Preparedness is stronger when the household can act even if a sensor, network connection or cooling appliance fails.
Set a relocation trigger before the cool room fails
A prepared home still needs an exit plan because shading, ventilation and portable equipment cannot guarantee that every building will remain tolerable. Before hot weather, agree where each person could go if the chosen cool room stops providing relief: another part of the building, a trusted nearby home or a suitable public place identified through current local advice. Check that the option is actually accessible at the likely time, and consider transport, keys, mobility aids, essential medicines, charging needs and pets. For a resident who depends on care, involve the person and their carer rather than leaving an informal plan in somebody else's head. Keep contact details on paper as well as on a phone, and make clear who will check in, who can enter the property and who decides to move. This is contingency planning, not a claim that leaving home is always safer; the destination and journey must be assessed against the same heat and health risks.
Decide in advance what evidence will trigger that contingency. Useful warning signs include the cool room failing to recover when outside conditions improve, essential equipment failing, safe ventilation becoming impossible, or an occupant becoming less able to drink, rest or follow the plan. Combine room observations with current UK heat-health advice and the person's condition; do not wait for a home thermometer to reach a self-invented universal threshold. Move earlier when delay would make transport or assistance harder, and call the appropriate health or emergency service if symptoms indicate urgent risk rather than treating relocation as medical care. On leaving, close the home in the safest heat-management state available, switch off only equipment that can safely be left off, and tell the named contact where everyone has gone. After the event, review whether the fallback location, journey and communication worked. A heatwave plan is stronger when it defines the point at which the building is no longer the sole line of defence.
