A heatwave affecting much of England and Wales, with temperatures expected to reach 38°C, is causing travel disruption across Transport for Wales (TfW) routes. TfW has advised passengers to check services before travelling and to allow extra time for journeys. TFW said it has introduced service alterations between Shrewsbury and Birmingham on Wednesday 12 August and Thursday 13 August following the Amber extreme heat weather warning issued by Met Office. Some services between Shrewsbury and Aberystwyth are being cancelled, as well as between Cheltenham Spa and Cardiff Central. National Rail warned the forecast weather may cause trains to be disrupted as heat can cause overhead lines to expand and sag, line-side fires and also rails to buckle.