Rainfall on UK’s wettest day on record could have more than filled Loch Ness

16 Oct 2020 12:46 PM

Saturday 3 October 2020 is now the wettest day on record since 1891 for UK-wide rainfall. It received the greatest rainfall in any single day averaged out across the UK, beating the previous record on the 25 August 1986.

Saturday 3 October was the wettest day in the UK rainfall record stretching back to 1891.

Dr Mark McCarthy is the head of the Met Office National Climate Information Centre. He said: “In climate statistics, 2019 will be remembered for possessing the UK’s hottest day, whereas 2020 will be associated with rainfall records. Saturday 3 October – the day which followed Storm Alex – currently holds the record for the UK’s wettest day in a daily series stretching back to 1891 – that’s over 47,000 days. The rainfall was very widespread resulting in average rainfall across the entire UK of 31.7mm, or to put it another way, if expressed as the volume of rain that is more than the capacity of Loch Ness – the largest lake in the UK by volume at 7.4 cubic kilometres of water. It is exceptional to have 30 to 50mm or more of rain falling so extensively across the UK – from the south coast of England to the north coast of Scotland – in a single day”. The previous record was 29.8mm on 25 August 1986.

At 7.4 cubic kilometres, Loch Ness is the largest lake in the United Kingdom by volume. Pic: Shutterstock.

Generally, the start to October has been very wet with the UK overall seeing 68% of its average rainfall for the month of October and England has been the wettest with 87% of its monthly average, in particular south east and central southern England already reaching 110%.

Commenting on 2020 Dr McCarthy added: “Remarkably, 2020 also has the UK’s third wettest day on 15th February with 27.2mm, from named storm Dennis during what then became the wettest February on record”.

More than 20 counties across the UK have already had 100% or more than their average October rainfall and many others are not far behind. Oxfordshire has been the wettest county compared to the 1981 – 2010 average with 148% average rainfall (107.1mm). Followed by Buckinghamshire reaching 139% (103.4mm) of its average rainfall, Berkshire with 138% (108.0mm) and Hertfordshire reaching 132% (96.9mm). Other counties already reaching 100% or above are Aberdeenshire, Angus, Banffshire, Bedfordshire, Berwickshire, Cheshire, City of London, City of Aberdeen, East Lothian, Essex, Gloucestershire, Greater London, Hampshire, Isle of Wight, Kincardineshire, Moray, Northamptonshire, Staffordshire, Surrey, Tyne and Wear, Warwickshire, Wiltshire and Worcestershire.

Wales, Scotland and Northern Ireland rainfall statistics remain at average numbers, and conversely Argyll and Bute has been significantly drier with only 29% of its average rainfall (70.7mm). The distribution of rainfall can be seen in the map below.

Already during October, many parts of the UK have recorded more than their monthly average rainfall for the month.