Last week, as Paris faced down its hottest day since records began, the city authorities declared their readiness. Since the notorious heatwave of 2003 that killed thousands across France, the capital has put in place a heat strategy: cooling areas, a checking system for vulnerable people, shady parks kept open all night.

Could these strategies actually work against a predicted record temperature of 42C (107.6F)? A study released this week shows that the world has never warmed faster than now. By 2050, the average temperature in the hottest month in Paris will rise by six degrees. This heatwave might be the new normal.

I take my dog for a quick morning walk before the pavement becomes too hot for his paws

Now that the heat has eased across Europe, it seems like time for some cool reflection on how effective the official advice actually was. Here’s what happened when I followed it.

9am, home, 20th arrondissement

Temperature outside: 29C

Strategy: shutter your house, spend three hours at low temperature

I wake in a sweat, having managed some fitful sleep with the help of a fan during one of the hottest nights in Paris history. Now it’s time to try to keep my tiny, 100-year-old house as cool as possible. Following the advice of the health department, I close all the shutters. Then I take my fluffy dog for a quick morning walk before the pavement becomes too hot for his paws. It’s pretty hot outside now, but nothing out of the ordinary: I’m mostly cranky and tired from the high temperatures overnight.

A woman fans herself inside a metro station in Paris as temperatures rise. Much of the transport system in Paris can be rendered unusable during heatwaves. Photograph: Sara Farid/The Guardian

Back home, the dog gets a big bowl of cold water, and I get ready for my day. According to the Paris heatwave plan, I have a plan to spend three hours at low temperatures to avoid adverse health consequences, and I’m prepared with other recommendations of the French health department: I’ve made a personal extreme-heat pack with a spray bottle to mist myself with water, a handheld thermometer and a large bottle of water. I’m ready.

10am, hotel

Temperature outside: 34C

Strategy: spend time in air conditioning

The temperature outside my front door has improbably climbed by five degrees in the last hour alone. The city is already uncomfortable: the narrow pavements and heavy traffic make it feel even hotter than 34C. There’s nowhere to hide from the exhaust fumes and the already fierce sun.

The official advice is to find air conditioning, so I walk to a nearby hotel. I’m already sweating when I arrive, but as soon as I step into reception my body temperature plunges uncomfortably. I’m also supposed to “eat in sufficient quantities”, which I’m interpreting to mean a buffet spread designed for hungry tourists and involving a lot of cheese. I look around at all the guests. They all passed a blissful night sleeping in 18C. They look refreshed, at ease, unflustered. One woman is wearing a scarf. I hate them.

People cool off in the Trocadero fountains across from the Eiffel Tower. Photograph: Pascal Rossignol/Reuters

12 noon, 20th arrondissement

Temperature: 38C

Strategy: use the Extrema app to seek out ‘cool islands’; avoid too much walking

If 34C was uncomfortable, 38C is nasty. As the heat rises from the bitumen, I fire up the city’s dedicated heatwave app, Extrema, which identifies 922 “islands of cool”. The first place it recommends is a library: presumably air-conditioned, unfortunately closed. The next suggestion is a nearby church, the Église Saint-Germain-de-Charonne, which is deliciously cool – but a small mass is being held, and I feel like an intruder, so I pop out to the adjoining cemetery. Here, the heat radiates off the polished gravestones in waves: it’s worse than the street. I drink from a fountain, but the water comes out piping hot. I had heard there was a water mister nearby, so I set out to find it, but fail. Extrema confirms it was only installed for two days.

Tramping around has driven my body temperature straight back up. The health department’s advice is to avoid physical exertion, such as walking long distances. I take the bus to a park.

1pm, Parc des Buttes-Chaumont

Temperature: 41C

Strategy: use a heat map to find green spaces

Families find respite from the harsh sun on the hottest day in Paris at Parc de Buttes-Chaumont. Photograph: Sara Farid/The Guardian

I’ve made a huge mistake. The bus is stifling, airless. My handheld thermometer has maxed out at 43C. I see pedestrians in the burning sunlight and I am jealous of them.

There’s an eerie hush as small family groups take refuge in the shade

Much of the transport system in Paris can be rendered unusable during heatwaves, with metro lines also regularly reaching dangerous temperatures. But 65% of Parisians do not own a car and have little option other than to endure it. I start to regret every decision I have made in life that led me to this bus.

Collapsing out at the Parc des Buttes-Chaumont, I expect some relief, but temperatures outside have now officially broken the previous record, from 1947, of 40.4C. The Buttes-Chaumont is one of the city’s largest parks, with waterfalls, sloping lawns and shady grottoes. Since 2015, it has been open 24 hours a day in summer. Over half of it is covered with more than 100 enormous old trees, making it one of the coolest places in Paris, according to the heat map. But 41C is 41C. There’s an eerie hush as small family groups and the odd shirtless or bikini-clad individual take refuge in the shade.

2pm, 19th arrondissement town hall

Temperature: 42C

Strategy: use town hall ‘refreshment rooms’; check in on loved ones

After the 2003 heatwave, Paris set up the Chalex service, which allows vulnerable people to receive telephone check-ups during extreme heat. The worst sufferers can be brought to a refreshment room at their local town hall. In the 19th arrondissement, that’s an air-conditioned meeting room: it’s cool enough inside, but the portable air-conditioner is beginning to struggle against 42C.

Emerging again into the blasting heat, I follow another of the health department’s rules: check in on your loved ones. In my case, that means texting my partner to ask how the dog is doing. The dog is lying in front of a fan, his fur gently ruffling. The dog is doing much better than me. I’m still radiating heat, primarily it seems from my face. But I’m also lucky that my loved ones are a young man and a resilient street dog. Elderly relatives, or people with reduced mobility who can’t necessarily make it to cooler spaces on their own, need human connection even more urgently in heat crises.

People cool off in the refreshment room in the 19th arrondissement’s town hall. Photograph: Sara Farid/The Guardian

3pm, 18th arrondissement

Temperature: 42C

Advice: help the vulnerable

In any city, heatwaves are hardest for those who lack shelter. For the hottest part of the day, I join a walking group of city officials and volunteers seeking out women who are living on the streets. The group provides hygiene kits and offers to take the women to cooler spaces. Leading the charge is Dominique Versini, one of the city’s deputy mayors.

I know I will live, best case, to see these problems get much worse. I feel a kind of existential dread

Versini says the heatwave presents serious problems for all homeless people, but particularly women, who are “in twice as much danger”. Exposed to high levels of violence on the streets and often dealing with trauma, she says, many are afraid to access services such as refreshment rooms and public baths where they could cool off.

The temperature hits its all-time maximum: 42.6C. The 18th is one of the densest parts of the city, and the photographer and I are struggling. My body is burning up, and now my anxiety is also rising sharply. I know this heatwave has almost certainly been caused by the human-created climate crisis. Greenhouse emissions are on track to reach a record high. I know I will live, best case, to see these problems get much worse. I feel a kind of existential dread. My muscles are starting to get sore.

We duck into a supermarket and I end up caressing my face with a range of chilled goods. Orange juice is pretty good but a glass jar of foie gras works best.

As advised by the health department, Megan Clement lingers in one of the air-conditioned supermarkets in the 18th arrondissement. Photograph: Sara Farid/The Guardian

5pm, Bassin de la Villette

Temperature: 42.6C

Advice: swim in the canal

On a normal day, I harbour no desire to jump into the Bassin de la Villette. I have seen the bikes, shopping trolleys and electric scooters being fished out of there, coated in muck. There are rumours of a crocodile.

But the outdoor pool alongside it, which is full of filtered canal water, has been in use since 2017 as part of a plan by the mayor, Anne Hidalgo, to make public waterways such as the Seine swimmable in time for the 2024 Olympics. Anyway, at this stage I would happily leap into a Siberian toxic dump-lake if I thought it would cool me down.

Unfortunately there’s a monstrous queue to get in, leaving would-be bathers baking along the pavement. Some have given up and are diving into the open canal. Everyone seems fine with this.

I eventually make it to the pool, and lower myself with a sound I didn’t know I was capable of: something between a whimper of fear and a groan of satisfaction. The water is a toasty 25.5C, and oddly slimy, but swimming feels incredible. I’m smiling for the first time in more than 24 hours. I try to avoid thinking about how much canal water I’m ingesting, and that E coli scare from a couple of years ago.

6pm, Place de la Bataille de Stalingrad

Temperature: 41C

Advice: douse yourself in cold water

The effects of the pool wear off more or less as soon as I get out of the water and cross a bridge over the canal in full sun. On the other side, Paris Plage – a sandless beach along the banks of the canal and the Seine, set out with deckchairs, bars and summer games – is a muted affair, with most activities shut down because of the heat. A few people languidly dangle their feet in the water.

But at the end of the canal, sweet relief. The city authorities have set up a temporary fountain that spouts water out of the top, not just from the taps below. I drench myself through. This is proper cold water, some of the first I’ve encountered today. It is extremely refreshing. I happily drip home on the metro.

8pm, hotel

Temperature: 38C

Advice: avoid alcohol

I am too traumatised to cook without air conditioning, so I head back to the same restaurant. The good news is that between breakfast, dinner and the refreshment room today, I have accumulated my required three hours at low temperatures. The bad news is the health department says I shouldn’t drink alcohol during a heatwave, and I could really use a beer.

I’m acutely aware that I’m healthy, and have some freedom and control over my movements. Many Parisians don’t

Rules are rules, so I stick with a carafe of water. It proves to be a bad choice: a beer would have at least been cold, while this tap water is somehow hotter than room temperature. I was starving but I can now only manage half of my meal, so I wander home to flop on the couch. It’s hot in my living room, but the shutters seem to have fended off the worst.

12 midnight, Square Sergent Aurélie Salel

Temperature: 33C

Advice: go to a 24-hour park

At midnight, it still hasn’t cooled down enough to sleep. At a mere 33C outside I reckon it’s fine to walk the dog, so off we go towards the Square Sergent Aurélie Salel, one of 13 parks open all night in summer. We pass half an hour there, with a clutch of other overheated young Parisians who are smoking half-heartedly beneath a tree, before turning back home. Jammed between two fans, I grab what sleep I can, but I don’t fully relax until 11am the next day when a thunderstorm breaks the spell.

I’m also acutely aware that I’m healthy and have some freedom and control over my movements. Many Parisians don’t: they have to move around the city according to their daily schedules, no matter the temperature. Some have no choice but to be outside all day during a heatwave. With its apps, cool spots and check-in services, the City of Paris is doing a lot to help them, but if my day taught me anything it’s that reality seems to be catching up with what research has long been telling us. The effects of rapid climate change are already here – and we are not ready.

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