We've used data science to predict which lines will be the hottest and coldest this year, to help you travel smarter.
By Making Moves London
June 24, 2025
The underground railway – a world first, opened in London in 1863 as a solution to reducing street congestion. Fast-forward 162 years, and approximately 2 million people use the Tube daily. To put this number into context, more people are travelling on the Tube each day than the entire population currently living in Iceland.
If you live in London or have visited for work or leisure, you have likely taken the Tube to get about, and we bet you have an opinion on it. Whether you are team tube or not, it’s a vital part of our capital’s infrastructure. With 2025 already breaking records for being the warmest and sunniest so far, we suspect temperature will be a hot topic.
Through Freedom of Information Requests and data obtained from London Datastore, we’ve used data science to predict which lines will be the hottest and coldest this year. So, whether you’re a daily commuter or an occasional traveller, this research reveals where you’ll most likely break a sweat—or need an extra layer. We hope this data helps you travel smarter, stay prepared, and continue making the most of a transport system that keeps the capital moving—even when the temperature rises or falls.
| Line | Max predicted temperature (degrees) | |
|---|---|---|
| 1 | Victoria | 32 |
| 2 | Central | 31.4 |
| 3 | Bakerloo | 30.1 |
| 4 | Northern | 29.1 |
| 5 | Piccadilly | 27.7 |
| 6 | Jubilee | 26.2 |
| 7 | Waterloo and City | 25.1 |
From 2021 – 2024, the Victoria line has consistently recorded the average hottest temperature, with an average of 28.1 degrees for the entire of 2024. The highest temperature recorded on this line was during September 2023, when the temperature rose to 31.25 degrees – hotter than the average monthly temperature of Athens for the same month. Our analysis predicts that this line could reach a maximum temperature of 32 degrees by 2025, with this peak occurring in August.
While the Victoria line is a sweltering one, it hasn’t always been the hottest. From 2013 – 2020, Bakerloo consistently remained the hottest, with the average temperature rising each year from 25.5 degrees (2013) to 27.1 degrees (2020). Since 2013, the Bakerloo line has recorded the hottest temperature of all lines on record, reaching 31.75 degrees in August 2019. To compare, cities such as Majorca, Istanbul and Los Angeles typically record lower temperatures during this time of the year. For 2025, we predict that Bakerloo will reach 30.1 degrees in August and 29.6 degrees in September.
We submitted a Freedom of Information request to Transport for London to better understand whether any of the lines had received complaints about being too hot or too cold. Unsurprisingly, the data show that Victoria has received the most complaints since March 2022, with a total of 78. 2023 received the highest number of complaints related to the line being too hot, with a total of 30 complaints received throughout the year.
Although all the data we have collected suggests the Victoria line is the hottest and most complained about, a 2024 YouGov poll of 1,010 adult Londoners places this line as the fifth most-liked tube line and the second ‘best’ line. While the poll didn’t ask why the lines were ranked as most liked or best, we’re surprised to see Victoria rank so highly, given its temperature issues.
So, why is the Victoria line so hot? According to Rail Magazine, several factors are driving higher temperatures. For one – the deep tunnels are getting worse as there is nowhere for the excess heat produced by the trains to escape. Secondly, the heavy and continuous use of the entire underground network over the last 162 years has transformed the once-cool clay into ovens. And thirdly – there are not enough ventilation shafts. Unfortunately, these issues aren’t quick fixes, so if you absolutely need to use this line during the hotter months, ensure you prepare accordingly. Transport For London offers the following advice on their website for travelling in the hot weather, including:
And, if you can take an alternative route, there are lines which are fitted with air conditioning. Although from 2024, London Transport Guru Geoff Marshall has created a handy map of all air-conditioned lines – just be aware that Piccadilly is due to be upgraded with air-conditioning at some point during 2025, so this line doesn’t yet feature on Geoff’s map.
Source – Geoff Tech – Air-Conditioned London 2024
With the lines hotting up in 2025, employers have a real opportunity to support staff wellbeing with a few simple adjustments – and in fact, going into the office could be the best way to beat the heat.
People Operations Lead at Making Moves, Emily Knight, shares her advice to employers whose team will be using the Tube in the hotter weather:
“When employees arrive at the office feeling overheated from their commute, it can be hard for them to feel or perform at their best. And during the hotter months, it’s the additional touches that make a real difference. We’re seeing a growing focus on facilities like showers, drying rooms, and hydration stations – all of which will help your staff after a hot commute.
Creating breakout spaces or quiet zones where people can relax and recharge helps maintain high energy levels and morale. One of the simplest long-term solutions we’ve seen work well, especially in London, is the Cycle to Work scheme. It gives people a healthier alternative to the Tube and offers benefits that last well beyond the summer.
Most modern offices feature air conditioning, so ensure your unit is set to a suitable temperature to help the team stay cool. Most London homes don’t typically feature air con, so this is a simple facility which can make a real difference.”
| Line | Min. predicted temperature (degrees) | |
|---|---|---|
| 1 | Waterloo and City | 17.5 |
| 2 | Piccadilly | 20.3 |
| 3 | Northern | 22.6 |
| 4 | Bakerloo | 22.9 |
| 5 | Central | 23.2 |
| 6 | Victoria | 25.4 |
| 7 | Jubilee | 26.2 |
Data for the following Lines (Circle, District, Hammersmith & City, DLR, Elizabeth, Metropolitan, London Trams, IFS Cloud Cable Car and all London Overground Lines) haven’t been included in our research, as individual temperature data for these lines were not available at the time of writing. The maximum temperature relates to the predicted average maximum temperature for year line across the year of 2025, specific months vary.
If you live or have visited London – or the UK for that matter, one thing you’ll know is that temperatures can drop and it can get cold. Very cold. To help you prepare for any cold journeys ahead, we have crunched the numbers to predict the tube lines with the coldest minimum temperatures in 2025. Waterloo and City take top place with a predicted minimum temperature of 17.5 degrees, 8.7 degrees lower than the predicted minimum temperature for the Jubilee line. While we don’t know the exact reasons why there is such a stark predicted temperature difference between Waterloo and City and the Jubilee lines, this could be due to the age of Waterloo and City – which opened in 1898, as well as Jubilee being one of the busier lines, which naturally creates more heat.
What is most surprising is the comparison between the temperature data and the complaint data. Since 2022, the Jubilee line has received the greatest number of complaints, with 11 complaints related to the line being too cold over this period. Piccadilly comes in second with eight complaints relating to the cold temperature since 2022, followed by Northern with seven. The data for all temperature complaints across the underground lines can be found below:
| Year | Bakerloo | Central | Jubilee | Northern | Piccadilly | Victoria | Waterloo and Central |
|---|---|---|---|---|---|---|---|
| 2022 | 0 | 7 | 2 | 2 | 4 | 29 | 0 |
| 2023 | 1 | 3 | 5 | 3 | 4 | 30 | 0 |
| 2024 | 3 | 9 | 3 | 10 | 19 | 0 | |
| 2025 (YTD) | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Total | 4 | 19 | 10 | 15 | 8 | 78 | 0 |
Data provided by Transport For London via a FOI request. Data correct as of 08/04/2025
| Year | Bakerloo | Central | Jubilee | Northern | Piccadilly | Victoria | Waterloo and Central |
|---|---|---|---|---|---|---|---|
| 2022 | 0 | 1 | 1 | 3 | 1 | 0 | 0 |
| 2023 | 0 | 1 | 3 | 1 | 5 | 0 | 0 |
| 2024 | 0 | 2 | 4 | 3 | 2 | 0 | 0 |
| 2025 (YTD) | 0 | 0 | 3 | 0 | 0 | 0 | 0 |
| Total | 0 | 4 | 11 | 7 | 8 | 0 | 0 |
Data provided by Transport For London via a FOI request. Data correct as of 08/04/2025
Recent analysis from The Telegraph has found that compared to 10 major cities, London’s transport prices are the highest in the world. The below table from the newspaper shows the price of tickets compared to other countries:
| City | Single ticket in central zone/s | 24-hour or one-day ticket | Length of metro system in miles* |
|---|---|---|---|
| Seoul | 77p | N/A | 223 |
| Tokyo | 95p | £4.23 | 121 |
| Madrid | £1.24 | £8.24 | 182 |
| Paris | £1.65 – £2.07 | £9.92 | 152 |
| Milan | £1.82 | £6.28 | 70 |
| Washington DC | £1.78 | £10.65 | 129 |
| Barcelona | £2.29 | N/A | 248 |
| Berlin | £2.15 – £3.14 | £8.19 – £10.17** | 97 |
| London | £2.80 – £2.90 | £8.90 – £15.30** | 250 |
Source – The Telegraph, 2nd March 2025 * Excludes overground rail services which may be included in the ticket price / ** Depending on zones.
Furthermore, we have found that all cities mentioned in the analysis, except Berlin and some lines on the Paris metro, either have air conditioning or a chilled water-cooling system, providing passengers with a means to cool down during the hot months.
So yes, the data shows that the Tube can run too hot and too cold at times, and certain lines are consistently driving the most temperature-related complaints. We also know that London’s public transport isn’t cheap — in fact, it ranks as the most expensive in the world.
But despite the grumbles, we remain proud of our network. A recent Time Out poll of 18,500 global public transport users placed London’s transport system as fifth best in the world — and nearly 9 in 10 Londoners admit they love the capital’s public transport system, with the Tube at its very heart.
After 162 years of continuous service, it’s hardly surprising the system faces the occasional challenge. But the fact that millions still rely on and even celebrate the Tube shows just how deeply it’s woven into the fabric of city life. Long may it continue to carry London forward for another 162 years and beyond.
A Freedom of Information Request was submitted to Transport For London for complaint data relating to the lines being too hot or cold, made between 2022 and March 2025. This data has been combined with data obtained from Transport for London via the London Datastore for individual tube temperature data from 2013 to 2024. Sub-surface lines have not been included as the temperature for all sub-surface lines had been combined by Transport For London. Individual temperature data for these lines is not available at the time of writing. The full dataset can be found here.
A data science model was then applied to forecast individual tube temperature data for the whole of 2025. Data for 2025 so far has been included in this forecast, as it has not yet been made available by Transport For London.
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