Temperatures in London are set to reach a humid 32°C this week, making it hotter than Ibiza, with Monday expected to be the year's warmest day so far.

With Tube ridership hitting up to four million daily, many commuters will face sweltering conditions on the Underground.

Rail travel experts JRPass submitted a Freedom of Information request to Transport for London (TfL) in a bid to uncover the hottest tube lines, and to reveal which service has received the most heat related complaints.

As reported by the BBC, JRPass’s FoI request has revealed that the Victoria line is the hottest tube line in the Underground network.

The hottest month in the Underground is September, where temperatures on the Victoria line reached 31.25°C.

The median temperature in Ibiza in the second week of August is 31°C, making the Victoria line in September hotter than the Spanish island in its summer months.

The Victoria line accounted for 61.22 per cent of all complaints across the Underground network related to excessively high temperatures.

The average platform temperature across 2023 was 28.27°C.

Between June and October, the average temperature on the Victoria line was above 30°C, with the highest temperature recorded in September at 31.25°C.

To address these high temperatures, TfL responded to the FOI request, stating it has: "removed heat from our station and tunnel environment by installing new ventilation or cooling solutions", including doubling the capacity of its 13 ventilation shafts on the Victoria line.

Ranking second is the Central line, with an average temperature of 26.78°C.

The hottest month recorded on the Central line was September, where temperatures soared to 30.89°C.

Whilst in third and fourth place are the Bakerloo and Northern lines, with an average temperature of 25.98°C and 25.38°C respectively.

Regarding the Central line, TfL responded: “On the Central line we have installed solar reflective material on the external surface of train roofs and solar reducing films on windows to minimise solar gains into the carriages.”

The coolest lines in the Underground network are the air-conditioned Circle, Hammersmith & City, District and Metropolitan lines (sub-surface lines), with an average temperature of 19.32°C.

This makes these services the best lines for Londoners to use to beat the heat this week.

JRPass’s FoI request to TfL has revealed that the Victoria and Central lines have received the most complaints so far in 2024.

Both lines received four complaints respectively regarding temperatures being too high on the line.

In second place is the Northern line with three complaints, followed by the Bakerloo line with two.