The London Underground is the last place most people want to be during a heatwave, yet millions will brave the network this week as temperatures hit 35C. A Red Extreme Heat Warning is in place for Wednesday, June 24, making journeys on non-air-conditioned lines particularly uncomfortable.
Which Tube Lines Have Air Conditioning?
Only four lines are fully air-conditioned: the District, Circle, Hammersmith & City, and Metropolitan lines. These are sub-surface lines, meaning they run in shallower tunnels or above ground, making installation easier. The Elizabeth Line also offers full air conditioning, but it is technically not part of the Tube network. The London Overground is almost completely air-conditioned, as are London Trams and Thameslink services. Newer DLR trains are air-conditioned, but some older trains remain in service without it.
Why Most Lines Lack Air Conditioning
Transport for London faces significant challenges due to the age of the network. The oldest tunnels date back to the 1800s, making it incredibly difficult and costly to improve airflow. According to Engineering and Technology magazine, building new ventilation shafts on the deepest lines would be “an incredibly expensive task.”
The Victoria line is particularly notorious, with platforms known to reach 30C between June and October. TfL has attempted cooling measures, such as larger ventilation shafts and mechanical chillers at busy stations, but these are limited.
Future Air-Conditioned Trains
The Piccadilly Line is set to roll out new trains by the end of 2026 or early 2027, which will be air-conditioned. Meanwhile, TfL is seeking government funding for new Bakerloo line trains by 2030, which would also feature air conditioning. For immediate relief, commuters might consider train services like Southeastern’s new fleet or Southern, which do offer air conditioning.
