The Victoria Line is the hottest on the Tube network with average temperatures topping 30C last summer, according to TfL data.
Platform temperatures across the year averaged 28.2C. The Central and Bakerloo lines were the next warmest with average 2023 temperatures of 26.7C and 26C.
The coolest were the air-conditioned Circle, Hammersmith & City, District and Metropolitan lines at a far more pleasant 19.3C.
Nick Dent, TfL’s director of customer operations, said: “We’re working hard to ensure our transport services remain resilient in the face of more extreme and frequent hot weather events.
“We have implemented energy- efficient solutions on new trains, which save energy and reduce the heat generated.
This includes air conditioning, which now covers 40 per cent of the Underground network, enhanced tunnel ventilation systems on both the Victoria and Jubilee lines, and on the Central line we have installed solar reflective material on train roofs and films on windows to keep the carriages cooler.”
In 2013 the Victoria line's average temperature was recorded at 21.9C, with temperatures rising more than 6C in a decade.
The Victoria line was one of the deemed the hottest Tube line in 2023 as well, alongside the Central line. It never dropped below 24C in 2022.
The Victoria line, which never comes above ground for the duration of its 13 miles between Walthamstow Central and Brixton, attracted more than half of all complaints that TfL catalogued as “temperature — too hot” in 2023.
Platform temperatures on the Tube are routinely monitored using data loggers, according to TfL.
