Our Ref:         FOI-0149-1819

Thank you for your request received on 18 April 2018 asking for information about temperatures on the London Underground.

Your request has been considered in accordance with the requirements of the Environmental Information Regulations and our information access policy. I can confirm we do hold the information you require.

London Underground records temperatures across the parts of the Tube network where we understand that heat can be a problem, in order to inform our cooling initiatives.

We are making good progress towards cooling the Tube, with a number of projects underway across the network to provide additional cooling systems. Our investment in cooling the Tube includes improving ventilation systems at our stations and introducing new air-conditioned trains. We have already introduced air-conditioned trains on the Circle, District, Hammersmith & City and Metropolitan lines as part of the Four Lines Modernisation programme.

The Deep Tube Upgrade Programme will bring the first walk-through air-cooled trains on to the deep-level Tube network with the first trains due to be introduced in the 2020s. Until then, we continue to seek innovative solutions to reducing temperatures during the summer months on the deep-level lines. We have implemented energy efficient solutions such as regenerative braking on new trains, which saves energy and reduces the heat generated. We have also installed ventilation and cooling solutions around the network to try to improve the environment in stations and tunnels. More information on the Deep Tube Upgrade Programme can be found on our website:

https://tfl.gov.uk/campaign/tube-improvements/what-we-are-doing/improving-the-trains

Please find the average monthly temperatures by line in the table below (January - December 2017):

Year Month Bakerloo Central Jubilee Northern Piccadilly Victoria W&C SSL (Sub-surface lines)
2017 January 23.4 21.55 17.5 21.54 18.9 20.51 18.19 11.99
2017 February 24.27 22.38 18.58 21.87 19.69 21.7 18.86 13.3
2017 March 25.66 24.29 20.56 23.09 21.28 23.63 20.46 15.98
2017 April 26.7 25.59 22.82 24.1 22.67 23.96 21.25 17.79
2017 May 27.66 26.95 23.69 25.02 23.82 25.4 22.53 20.26
2017 June 29.99 29.76 25.96 27.3 26.35 27.65 24.91 24.15
2017 July 30.87 30.61 26.56 28.15 27.18 28.54 25.53 24.67
2017 August 30.3 30.02 25.89 27.88 26.81 28.18 25.17 23.57
2017 September 29.42 28.8 24.92 27.04 25.69 27.51 24.2 24.35
2017 October 28.36 27.87 24.33 26.37 24.67 28.04 23.5 23.18
2017 November 26.23 25.24 22.53 24.13 22.34 26.68 21.14 16.04
2017 December 25.05 23.11 20.96 22.37 20.26 24.51 19.27 13.25

If this is not the information you are looking for please feel free to contact me.

Please see the attached information sheet for details of your right to appeal.

Yours sincerely

Gemma Jacob
FOI Case Officer
FOI Case Management Team
General Counsel
Transport for London

[email protected]