Britain is set to be engulfed by a ‘monster storm’ of heavy rain and bad weather over the next five days. The storm, which stretches the entire width of the Atlantic, will bring heavy rain from tomorrow followed by more downpours over the weekend. Despite this, temperatures will be warmer than usual at around 20C due to low pressure to the west of Britain. Met Office forecasts expected up to 16mm of rain to fall an hour over parts of the south west from tonight before sweeping across Wales and along the south coast tomorrow. Thunderstorms are also expected in places.