UK heatwave: Rail passengers warned hot weather will disrupt trains

Southeastern links from London to Kent will be reduced, and trains to the South Coast will be slower

Weather watch: Southeastern says its longer-distance trains could be significantly delayed (Simon Calder)

The scale of disruption to rail travellers on Thursday because of extreme heat is becoming clear – with Kent and Sussex particularly badly affected.

"We strongly advise you to avoid travelling, if you can," is the blunt message from Southeastern.

The train operator, which serves southeast London and Kent, says: “Significantly fewer services will be running tomorrow, and many trains will be much busier than usual as a result.

“Those trains which do run will take longer to complete their journeys – particularly on our longer-distance routes.”

Rail passengers across southeast England have been urged to “consider changing their plans” on Thursday because of expected disruption due to high temperatures.

Network Rail is imposing speed restrictions on some lines to prevent the track buckling.

Temperatures in London may reach 38C on Thursday, which would pass the current record for a day in July recorded as 36.7C at Heathrow Airport in 2015.

The main line from London via Gatwick airport to Brighton will have speed restrictions as low as 20mph in places – about a quarter of the normal running speeds.

“We do expect a number of our trains to lose time between London and the South Coast,” said Govia Thameslink Railway.

Speed is most heavily restricted on lines where the rails have been recently installed, which is the case for much of the Brighton main line.

With Gatwick airport expecting a very busy day, airline passengers’ journeys could be jeopardised.

On routes from London Liverpool Street to Essex, Suffolk and Norfolk, Greater Anglia is running fewer trains on Thursday afternoon and evening.