The Central Line will be the hottest on the tube during the UK heatwave

The Met Office has warned that a heatwave will hit the country this week

A heat map showing the hottest (red) and coolest (blue) underground lines based on data gathered throughout August 2013, taken between 4pm and 7pm (credit: TFL) (TFL)

The thought of being stuck in a sweaty, sweltering carriage on the Tube might just be every Londoner’s worst nightmare.

As temperatures soar this week in a heatwave, commuters in the capital city would do well to avoid the Central Line, which has been named as the hottest route on the Underground.

The Met Office has issued a heatwave alert for conditions beginning this afternoon and expected to last until Thursday morning. Temperatures are expected to soar across the UK as sunny spells spread. In the capital city, temperatures could reach a height of 33 degrees.

For commuters worried about wilting in hot train carriages, Transport for London has told The Independent that the Central Line tends to be the hottest route every year and that they expect the same will be the case this week.

The Metropolitan, Circle and Hammersmith & City Lines are all operating new air conditioned trains. Mechanical chiller units have also been installed at Oxford Circus and Euston stations to help passengers as temperatures soar.

David Waboso, Capital Programmes Director at London Underground, says that TfL is trying to make a number of improvements to make journeys more comfortable for passengers during summer months: “As part of our plans to improve every single journey we are making real headway towards cooling the Tube.

“However, there is still work to do. Cooling the deeper lines of the Tube is a big engineering challenge, but we’re making significant steps forward for the next generation of Tube trains on the Piccadilly line, we will include a requirement for air conditioning.”

He added that new, air-conditioned trains will make up 40 per cent of trains by 2016.

Commuters throughout the country were today warned to expect some delays to train services as the heatwave could see some tracks buckle.

First Great Western services in the Thames Valley area will be disrupted from midday to 8pm on Tuesday.

A First Great Western spokesman said: "Network Rail has advised that, due to the anticipated exceptionally hot weather, there will be speed restrictions to protect track points in the Thames Valley region on Tuesday 30 June 2015.

"As a result there will be no fast trains between London Paddington and Bourne End or Henley-on-Thames from 12-8pm.

"Trains from London Paddington will terminate at Twyford for a connection with a branch line train to Henley-on-Thames, which will remain on the branch line.