Frank Saunders, chief meteorologist at the Met Office, said: “The heavy rain is likely to reach southeast England and parts of East Anglia later today and then spread north and west overnight, reaching much of eastern, central and southern England by Monday morning and then expected to last much of the day.“Many areas will see between 25 and 40 mm of rainfall with isolated pockets perhaps seeing as much as 50 to 70mm [which is well in excess of the whole month’s average].”This could increase the risk of flooding and hazardous driving conditions. The heavy rain will be accompanied by strong to gale force northerly winds – the unusual direction could increase the likelihood of localised impacts from wind too, with some damage to trees for example and likely closure of some bridges. “Lastly it will be an unseasonably cold day – perhaps cold enough to produce some wet snow on high ground although this seems unlikely to settle.” Britain has been issued a power cut warning as the London and the south east is set to be hit by a barrage of torrential rain, gales, closed roads and flooding.The Met Office warned temperatures will drop to 4C on Monday, but a wind chill in the air will leave it feeling as cold as -1C, and there is also the possibility of snow appearing in high areas.Meteorologists are predicting gale-force winds and around two-and-a-half inches of rain starting Sunday night and could lead to major travel disruptions across the south and east of England.Severe flooding and sudden power cuts could strike Monday, with a yellow weather warning in place from midnight through to Tuesday.Several flood warnings and alerts have been issued Sunday, with heavy rain and strong winds expected in many southeastern areas of England, London and the South East on Monday.The East Midlands, East Anglia and Yorkshire and Humber are also expected to be affected.Flooding and spray on roads is likely to lead to hazardous driving conditions and even some road closures, as well as delays or cancellations to train and bus services, the Met Office say.Homes and businesses also could be flooded, causing damage to buildings, along with power cuts and transport services hit. Trees and other structures could also be damaged, leaving roads and bridges closed, experts warn.Officials at the Environment Agency warned residents to be “prepared” for the possibility of flooding on the River Kennet and the Lower Avon in Wiltshire, Dorset and Hampshire.After temperatures hit 26C earlier this month, next week is predicted to not rise above 5C in most of the country. The heatwave of last week will become a distant memory as the temperature plummetsCredit:Hugo Michiels/London News Pictures Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings.