Britain faces one of its hottest days on record today as temperatures could hit 38C and rail passengers were urged to only make essential journeys.The Met Office has extended the area of its rare 15-hour amber 'extreme heat' warning - only its second since 2022 - which came into force at 9am this morning.The warning initially covered parts of central and southern England, but at 10am it was extended further west - where the highest temperatures are now expected.The whole of England is separately under a UK Health Security Agency (UKHSA) amber heat health alert until tomorrow night, which warns of a 'rise in deaths'.Chiltern Railways and East Midlands Railway both told passengers to 'only travel if essential' with the UK's sixth heatwave of the year expected to cause delays.Reduced services were also confirmed by c2c, CrossCountry, Great Western Railway, Northern, Transport for Wales and West Midlands Railway as temperatures soar.A 38C (100F) high today would make it Britain's joint fifth hottest day on record – tying with that same temperature in Norfolk on June 26, which is the current 2026 high.It comes as fire chiefs said 1,017 wildfires have been recorded in England and Wales so far in 2026, the same as the record-breaking total for the whole of last year.Prime Minister Andy Burnham chaired a meeting of the Government's emergency Cobra committee yesterday in response to the ongoing hot and dry weather. Cattle graze near the Oxfordshire village of Uffington this morning as the heatwave continues The updated area within the Met Office amber warning for 'extreme heat' from 9am to midnight A person walks through a parched park in Birmingham today as the hot weather continues White Horse Hill in Uffington, Oxfordshire, is still green in places but surrounded by dry fields People stand beside St Michael's Tower on Glastonbury Tor to watch sunrise this morning A beautiful sunrise over the Oxfordshire countryside at Dunsden Green this morning