Third heatwave of the year sparks rail warning as temperatures set to hit 35C

The UK is officially in its third heatwave of the year, with temperatures expected to reach 35C in some areas – prompting a rail company to urge passengers to travel only if essential. The Met Office confirmed that parts of southern England entered heatwave conditions on Monday, with the highest temperature recorded that day at 34C in Teddington, south-west London. Met Office Deputy Chief Forecaster Steven Keates said: 'Parts of the UK are entering heatwave conditions: the third heatwave in the UK so far this year. However, unlike the May and June heatwaves, we are not expecting this heatwave to be record-breaking.' The hot, dry spell is forecast to be less humid than June's heatwave, with lower peak temperatures and fewer exceptionally warm nights, but temperatures in southern England are still expected to climb into the low 30s, possibly reaching 34-35C later in the week. As the mercury rises, Network Rail has advised passengers to only travel if their journey is 'essential', citing the strain extreme heat can place on infrastructure. With motorists also facing scorching conditions, experts have offered guidance on staying cool without wasting fuel. Mike Fazal, motoring expert and CEO of Leasing.com, pointed to the '45mph air-con rule' as a way to save fuel while remaining comfortable. 'Below that speed, it's usually more fuel efficient to open your windows and let air flow through the cabin,' Fazal explained. 'Once travelling faster than around 45mph, especially on dual carriageways or motorways, open windows create aerodynamic drag that makes the engine work harder. At that point, using the air conditioning can actually become the more fuel-efficient choice.' Studies cited by Fazal indicate that air conditioning can raise fuel consumption by about 10%, whereas driving with windows open at higher speeds can push fuel use up by 20%. He also warned drivers against wearing inappropriate summer footwear such as flip-flops, clogs or Crocs, which can slip off or reduce pedal feel, compromising vehicle control. The heatwave is the third this year, following similar spells in May and June, but forecasters say it is not expected to break records. Nonetheless, the combination of high temperatures and travel warnings has left many Britons weighing up their plans for the week ahead.