Communities along the length of the east coast of England, including Lincolnshire, should be braced for the most serious coastal tidal surge for over 30 years.
The Environment Agency and Met Office are warning that gale-force winds, large waves and a tidal surge caused by low pressure will combine with high tides today (Thursday), throughout Friday and into Saturday morning, bringing a risk of significant coastal flooding.
In some places, sea levels could be as high as those during the devastating floods of 1953.
However, flood defences built since then – including the Thames, Deptford and Hull Barriers – mean that many parts of the country are much better protected than in 1953
The Environment Agency issued a severe flood warning – its highest category – to homes and businesses near The Quay in Sandwich, Kent, for high tides at 12.43am and 1.06pm on Friday.
At present, there are also 16 flood warnings and 52 flood alerts in place.
In Lincolnshire, there are flood alerts for the Lincolnshire coast from Tetney Haven to Gibraltar Point, and areas near The Wash from Gibraltar Point to Admiralty Point and the tidal River Witham, River Welland and River Nene.
Areas most at risk include the North Sea coast from Northumberland down to the Thames Estuary and Kent.
The Environment Agency will be closing the Thames Barrier on Thursday night to defend London, in addition to operating other defences including those at Colne in Essex and Hull.
Dr Paul Leinster, Environment Agency Chief Executive, said: “Gale force winds and large waves along the east coast of England are forecast during Thursday and Friday, coinciding with high tides and a significant coastal surge.
“Flooding of some coastal communities is expected and some defences could be overtopped by the combined effect of high tides, high winds and a tidal surge.
“Coastal paths and promenades will be highly dangerous as there is an increased risk of people being swept out to sea.
“The Environment Agency is monitoring the situation closely, working alongside partners including the emergency services, Met Office and local authorities. Environment Agency teams are out on the ground checking that flood defences and barriers are in good working order, monitoring sea levels and issuing flood warnings.
“People should check the Environment Agency website or follow @EnvAgency and #floodaware on Twitter for the latest flood outlook, and to sign up to receive free flood warnings.”