The villages suffered extensive damage after flash floods caused by an exceptional amount of rain that fell over eight hours that afternoon.

A study commissioned by the Environment Agency from hydraulics consulting firm HR Wallingford concluded that it was among the most extreme ever experienced in Britain.

At midday on 16 August 2004, heavy thundery showers had developed across the South West due to a weak disturbance to the northeast of the United Kingdom.

On 16 August, warm air picking up moisture – due to residual heat from the Atlantic Ocean – travelled toward the Cornish coast as prevailing winds.

Upon contact with the topographically vertical coast, these winds experienced a strong up-drafting force, thus causing internal moisture to rise and consequently cool as a string of storm clouds.

With convergence[4] and coalescence, enhanced moisture levels resulted in heavy rainfall on the afternoon of 16 August 2004.

At the peak of the downpour, at about 15:40 GMT, 24.1mm of rain (almost one inch) was recorded as falling in just 15 minutes at Lesnewth, 2.5 miles (4 km) up the valley from Boscastle.

75 cars, 5 caravans, 6 buildings and several boats were washed into the sea;[citation needed] approximately 100 homes and businesses were destroyed, and some had to be demolished; trees were uprooted and debris were scattered over a large area.

In an operation lasting from mid-afternoon until 2:30 am, a fleet of 7 Westland Sea King helicopters rescued about 150 people clinging to trees and the roofs of buildings and cars.

On 1 May 2005, the official reopening of the village, wooden fences were used on the bridge to temporarily replace the stone walls.

After an afternoon of intense localised rainfall, and a week of steady rain everyday, a small flood happened on 21 June 2007.