What are the best Paris Metro lines to use during a heatwave?

Phileas Gatsby is the online alias of an IT worker fascinated by transport. 

The Twitter user whose face is disguised with a 'crazy' emoji has compiled somewhat of a masterpiece with a recent thread on the Paris Metro system. 

"I have been interested in railways since I was little," he told The Local. 

"I have used the Metro a lot and learned a lot by observing and asking questions whenever I have the opportunity."

As the French capital endures a heatwave, with temperatures close to 40C, residents are advised to avoid overexerting themselves - and travelling on public transport is probably ill-advised. 

But should you consider making a journey across the city on the Metro, @OnTheRodPhileas has some sound advice on which lines to take. 

[Thread spécial #canicule et #Transport]

[Édition été 2022 !] Quelles sont les lignes de métro #RATP les plus fraîches de cette #Canicule2022 ? 🚇❄️

Trucs et astuces pour passer des voyages plus agréables, même dans les lignes réputées chaudes 🌡️ et étouffantes 🥵 ! 😉 pic.twitter.com/OThe9NNdyV

— Phileas Gatsby (@OnTheRodPhileas) June 17, 2022

Here is his line-by-line breakdown:

Line 1: 

There is air conditioning on these trains, but it works "super badly".

"Depending how busy it is, you risk getting very hot". 

Lines 2, 5, 9: 

"You will not find better than these three lines," writes Phileas. 

He describes these options as having cool, refrigerated air. 

Line 3 

Describing this line, Phileas writes simply "Ça passe". 

This line does not have refrigerated air conditioning but a system called Ventilation Mécanique Forcée - where air from the underground tunnel surrounding the train is pumped in. During a heatwave, this doesn't necessarily cool things down much. 

He recommends sitting on non-motorised coaches. On almost all line 3 trains, this means you should place yourself in carriages 2 or 4. 

However on trains n° 129, 130, 131, 132 (the number is listed on the front of the train just below the driver's windscreen), you should sit in either the first or last carriage to get the coolest temperatures. 

Line 3bis 

This line does not have air conditioning but you can cool down by opening the windows. 

Phileas says the temperature is cool however because so few people use it. The ideal position is in the central carriage. 

Line 4 

Line 4 uses Ventilation Mécanique Forcée. Avoid this line if it is busy. If relatively empty, you can open the windows and get a real rush of air as the train moves. 

Line 6 

Avoid this line, which Phileas describes as an "oven". 

There is no cooling system besides opening the windows. 

Much of this line is open air rather than underground, which means the train is heated by the sun. 

Lines 7, 8, 13

These lines are average to poor in terms of temperature. 

Line 8, which runs overground for significant sections, gets particularly hot. 

For the coolest journey, try to get a seat in carriages 2 or 4. 

Line 7bis 

Although this line uses Ventilation Mécanique Forcée, it is extremely cool because it is not busy and is located deep underground. 

Line 10 

Phileas' verdict: "Hot".

For coolest temperatures, place yourself in either the first or last carriage. 

But the lack of ventilation and heaving crowds mean that it will still be sweltering. 

Line 11

This line is also likely to be hot and has a distinct lack of air conditioning. 

Try to position yourself in carriage 2 or 3. 

Line 12

These trains are hot with no ventilation system other than windows. 

Line 14 

There are three different kinds of train that run on Line 14 - which is deep underground, which helps to some extent with temperatures. Although during a heatwave, it still gets hot. 

The MP89 is recognisable because of its green-ish seats. These have Ventilation Mécanique Forcée and are best avoided when busy. 

The MP05 has multicoloured seats and air conditioning - although the air conditioning system functions terribly and so it gets warm. 

The MP14CA trains have orange and blue seats. These are new models with excellent air conditioning that should keep you cool throughout the journey. 

Whatever train you take on line 14, try to take a "train long", as these are cooler. When waiting on the platform, go to the bit where the floor is marked in red paint - this area is not serviced by shorter trains. 

General advice 

Non-motorised carriages are cooler. 

🚨 Pro tips plus global 🚨

Les voitures repérées par les lettres S, A et B en bas de caisses, sont les voitures "remorques", c'est à dire sans moteurs, et donc risquant d'être plus fraîches.

(A contrario, les motrices sont : M, N, NA) pic.twitter.com/Qp2XHZOu1t

— Phileas Gatsby (@OnTheRodPhileas) June 17, 2022

When you are waiting at the platform, you will be able to see letters at the bottom of each individual carriage. 

If you see S, A, or B written, this means that the carriage is motor-less and likely to be cooler. 

You can follow Phileas @OnTheRodPhileas on Twitter. He regularly posts gems about French transport, urbanism and architecture.