Heatwave in Madrid: what to expect and how to stay safe

Madrid has a problem coastal cities do not: there is no sea to moderate anything. The city sits at 650 metres on the central plateau, more than 300 kilometres from any coast. When Saharan air arrives, nothing cools it down.

On top of that comes the urban heat island. Asphalt and concrete absorb radiation during the day and release it at night, so the centre can run 4 to 6 °C hotter than the outskirts at three in the morning. Hence the tropical nights: minimum temperatures that never drop below 25 °C, sometimes for a week straight.

This matters more than it sounds. The human body recovers from heat overnight. When the minimum stays above 25 °C, that recovery does not happen, and risk accumulates day after day. That is why AEMET warnings account for night-time minima, not just daytime peaks.

The most exposed areas are the southern and south-eastern districts — Villaverde, Vallecas, Usera — with less tree cover and more paved surface than the north of the city.

Every day of a heatwave strips moisture from vegetation. After four or five days, scrub and pine reach a point where a single spark — a cigarette, a shard of glass, farm machinery — is enough to start a fire that advances faster than a person can run.

The map below shows thermal hotspots detected by satellite over the last 48 hours. Each dot is a temperature anomaly seen from orbit, not necessarily a forest fire: it may be agricultural burning or an industrial facility. What matters is the pattern — dots in a line usually mean a front advancing with the wind.

Around Madrid the risk concentrates in three specific areas: the Sierra de Guadarrama to the north, dense pine forest with tourist access that saturates at weekends; the Cuenca Alta del Manzanares regional park, very close to the city; and the Montes de Toledo to the south-west, outside the region but close enough that smoke reaches the capital on a south-westerly wind. The regional government restricts access and bans barbecues at high alert levels — check before setting out.

This is the part most people overlook. A heatwave stores an enormous amount of energy in the atmosphere. When cooler air finally pushes in, that energy releases all at once — and the result is not gentle rain but violent thunderstorms, hail and damaging wind gusts.

The pattern repeats every summer: five days of unbearable heat, and on the sixth a storm that brings down trees and blacks out whole neighbourhoods. The end of a heatwave is, statistically, the most dangerous moment of the entire episode.

Telling heat exhaustion apart from heatstroke is not an academic distinction: the first is treated at home, the second is a life-threatening emergency whose mortality rises sharply with every minute of delay.

Heat exhaustion — pale, clammy skin, heavy sweating, weakness, nausea, headache, muscle cramps. The person stays conscious and oriented. Act: shade, fluids, loosen clothing, damp cloths. It usually improves within half an hour.

Heatstroke — and here is the decisive sign: the skin stops sweating and turns hot and dry, core temperature passes 40 °C, and confusion, incoherent speech, aggression or loss of consciousness set in. The body's cooling mechanism has failed completely.

For suspected heatstroke call 112 immediately and start cooling while help is on the way: shade, cold water on the neck, armpits and groin, remove clothing. Do not give fluids to anyone with altered consciousness — choking risk.

AEMET (Agencia Estatal de Meteorología) issues colour-coded warnings based not only on daytime highs but on overnight minima and the length of the episode. Those warnings trigger the National Plan for Preventive Action against High Temperatures.

• Drink before you feel thirsty. Thirst appears once dehydration has already begun. Avoid alcohol and very sugary drinks.
• Stay indoors between noon and 6 PM. If you are visiting historic sites, go at opening time or late afternoon — shade there is close to nonexistent.
• Shutters closed by day, ventilate at night. It sounds obvious and a great many people do exactly the opposite.
• Check on elderly people living alone. Most heat deaths happen indoors, not on the street. One phone call a day is a genuine prevention measure.
• Never leave anyone — or any animal — in a parked car. The interior passes 50 °C in under fifteen minutes.

In an emergency call 112. For non-urgent medical advice, 061.

• Check the storm for your town