The hot temperatures of the summer months can be challenging for our railway. South Western Railway and Network Rail Wessex are working together, as one organisation, to minimise the impact of hot weather, keep trains running, and ensure you can travel comfortably.
Travel advice
Advice for travelling in hot weather
We recommend that you carry a bottle of water with you when travelling in hot temperatures. If you need to refill your water bottle, there are free refill points at London Waterloo, Clapham Junction and Guildford stations.
Most of our trains have air conditioning but it’s worth carrying a fan. If there are issues with a train’s air conditioning then our guards will let you know, and you may wish to consider moving to a different carriage.
If you feel unwell when travelling on our trains
If you feel unwell while travelling with us, the best thing to do is to leave the train at the next stop. You can either speak to a colleague or use a station help point to get assistance.
Please do not use the emergency alarms on our trains, as this may stop the train and delay us helping you.
Travelling to the beach?
Plan your journey carefully if you’re travelling to Bournemouth or Weymouth to visit the beach. These stations, and the trains that serve them, get extremely busy in periods of hot weather.
It’s a good idea to buy your tickets in advance, as there may be large queues for ticket offices and ticket vending machines. Remember, you must buy a ticket before you board a train, or you could face a penalty fare of up to £100.
You should allow plenty of time to complete your return journey, as it might not be possible to board the first departing train. Check before you travel using a journey planner.
Please also be mindful about bringing large items of luggage and make sure it’s stored properly on the train. For more information on what you can bring with you on the train, you can read National Rail’s advice here.
Bournemouth is also served by CrossCountry services, so it’s a good idea to check their services too.
How hot temperatures affect the railway
Impact on tracks
The rails on our tracks are made of steel which easily absorbs heat, raising their temperatures up to 20 degrees hotter than the air temperature.
In May 2026, air temperatures reached over 35 degrees in London, and rails reached temperatures of more than 50 degrees. That’s hot enough to make them expand and buckle, making it unsafe for trains to travel over them. In these cases, we must stop trains running and carry out repairs.
On most of our network we use a third rail to power our trains. These rails, and the equipment connected to them, are also susceptible to high temperatures.
Impact on signals
High temperatures can affect signalling systems, the traffic lights of the railway.
We use track circuits and axle counters to tell our signallers where trains are, and they also control the signals themselves. Extremely hot conditions can affect how this technology works, and if a train driver or signaller notices a problem with our signals, we must investigate.
We might send a team to inspect the track, or slow trains down until we know it’s safe to run at full speeds. While this can cause delays, it’s vital that we ensure that our tracks and signals are working properly and that the railway is safe.
Impact on ground conditions
Hot and dry weather can even affect the ground that our tracks are built on.
Most of the railway in the south and southwest is built on embankments containing clay soil. When temperatures increase, vegetation near these embankments soak up a lot of water from the clay soil and it shrinks. This is called ‘soil moisture deficit’.
Tracks need to be level for trains to run at full speeds, and if the levels, or ‘track geometry’, isn’t right, we must limit our trains’ speeds to ensure they run safely. In the most extreme cases we have to slow trains down to as little as 5mph, and altered timetables are then needed to prevent delays spreading across our network.
Unlike buckled rails or issues with signalling equipment, there is no quick fix for track affected by soil moisture deficit. We must allow the clay soil to regain its moisture - when temperatures are lower and when we have more rain - otherwise the track will continue to move.
How we prepare for and respond to hot temperatures
When we’re alerted to hot weather
Working with the Met Office we keep a constant check on weather conditions. When temperatures look set to reach a certain level, we activate our Extreme Weather Action Team (EWAT).
The EWAT looks at how the hot weather will impact our network and plans a response to keep trains moving and keep customers safe. This might include putting engineers on standby where we might see track problems, preparing our coastal stations for larger numbers of customers, or making changes to the train service to ensure it’s as reliable as possible.
As soon as we think hot weather will impact your journey, we’ll issue travel advice at our stations, on our website, and through X.
Service alterations
Because of the impact that high temperatures can have on our track, signals and other infrastructure, we must carefully consider how we run our train services to keep the railway safe.
For example, if we think that a section of track might be affected by the heat, we may run fewer trains over it, to prevent it from causing disruption.
Temporary timetables may be used, which reduce the likelihood of delays spreading across our network and provide you with more certainty as to what trains are running.
How we prepare the railway for hot weather
We use a range of measures to minimise the impact of hot weather on the railway.
To monitor conditions in real time, we use sensors that let us know when parts of track are getting too hot. On parts of the network known as ‘hot spots’, we paint some of our rails white to reduce the heat absorbed and lower the risk of buckling.
On critical routes, such as the line between London Waterloo and Woking, we install reinforced concrete slabs to provide greater stability during extreme temperatures, making them more resilient in hot weather.
We have more than 1,300 miles of track on our network and carefully carry out a lot of vegetation management to ensure lineside vegetation doesn’t disturb the railway.
You can find out more about how the railway prepares for hot weather here.
