Commuters urged to carry water as thermometer soars and notorious ‘heat line’ becomes hotter than ever before
Transport for London is scrambling to keep passengers safe as temperatures on the capital’s Underground network reach unbearable levels, with the Victoria line now officially crowned London’s hottest tube line.
The transport authority is advising all passengers to carry water bottles this weekend as London continues to bake, with temperatures forecast to reach 31°C on Saturday across the capital.
Fresh data reveals the Victoria line has overtaken the notorious Central line as the Underground’s most sweltering route, with average temperatures hitting 28°C last year and peak temperatures reaching a staggering 31°C in September.
‘Like Walking Into An Oven’
Commuters have described the experience of stepping from the platform into Victoria line carriages as “like walking into an oven”, with the line never dropping below 24°C even during winter months.
The alarming temperature rise has been dramatic – historical records show the average temperature was just 18°C in January 2013, meaning the line has become 10 degrees hotter in just over a decade.
Transport for London’s Director of Customer Operations Nick Dent acknowledged the organisation is “working diligently to strengthen its transport services in light of increasingly extreme and frequent hot weather.
Deep Tunnel Nightmare
The problem is particularly acute on the Victoria and Central lines due to their construction. TfL Senior Press Officer Chris Clements explained: “With the Victoria and Central lines, they are some of the deepest Tube lines on the network, going through thick London clay. This clay acts as a heat insulator, meaning these lines get hotter than other tube lines.”
When the tunnels were first built, clay temperatures were around 14°C – they’ve now risen to between 19-26°C, with air temperatures in tunnels reaching as high as 30°C.
The situation has become so severe that temperatures as high as 47°C were reported during the 2006 European heatwave, well above the 30°C legal limit for transporting cattle.
Million-Pound Cooling Battle
Transport for London has invested millions in attempts to cool the overheated network:
- Doubled capacity of 13 ventilation shafts on the Victoria line
- Installed air cooling units and mechanical chillers at busy stations like Oxford Circus
- Using groundwater from underneath Victoria station to cool platforms
- Tapping into the aquifer beneath Green Park for station cooling
Despite these efforts, the heat continues to rise. TfL’s engineering interventions have shown limited success, with the Victoria line experiencing the highest average temperatures ever recorded in the first quarter of 2024.
Weekend Warning
With Friday’s temperatures already reaching 27°C and the weekend forecast showing even hotter conditions ahead, Transport for London is taking no chances.
The advice to carry water comes as posters across the Underground network advise passengers to bring bottles to help keep cool.
For those looking to avoid the worst of the heat, the Jubilee line offers relief with an average temperature of 22°C, while the Waterloo & City line maintains 21°C. The air-conditioned sub-surface lines – Circle, District, Hammersmith & City and Metropolitan – remain the coolest options.
No Quick Fix In Sight
The long-term outlook remains challenging. While new trains are more energy efficient and produce less heat, and air-conditioned Piccadilly line trains are due to arrive next year, TfL has said major improvements for the deep-level lines won’t be possible without significant government investment.
Transport for London’s engineers are “in a race against time and physics, trying to cool a system that was never designed to be cooled”, with climate change only set to make the underground sauna more challenging to manage.
For now, commuters are left to sweat it out, armed with water bottles and the hope that they won’t get stuck between stations when temperatures peak.
As one regular Victoria line passenger put it: “We’re basically travelling in mobile saunas. At least in a real sauna, you can leave when you want.”
STAYING COOL ON THE TUBE: TOP TIPS
- Carry water at all times
- Travel during off-peak hours when possible
- Use air-conditioned lines where available
- Wear light, breathable clothing
- Consider alternative routes using cooler lines
- Don’t travel if feeling unwell
Unknown author (Wikimedia Commons). “Victoria Underground Station.” Photo taken in 2025 at Victoria Underground station, London, shared as “VIctoria Underground Station – 52872106282.jpg” on Wikimedia Commons. Licensed under Creative Commons Attribution‑ShareAlike 3.0 Unported (CC BY‑SA 3.0)(https://creativecommons.org/licenses/by-sa/3.0/)
