Based on a daily total of 41.8mm at St James’s Park, the estimated return period based on rainfall intensity is approximately 50- to 100-years.įollowing the floods on 25 July, two hospitals and eight tube stations were closed for a day (Economist, 2021). The historical rainfall records were obtained from gridded rainfall between 19 from NOAA Physical Science Laboratory, CDC Global Unified Gauge-Based Analysis of Daily Precipitation dataset. JBA’s estimated return period for a daily total of 41.8mm is approximately a 1-in-50 to 1-in-100-year event.įigure 1: A General Pareto Distribution curve was fitted to historical records available for the closest location (51.75, -0.25) to St James’s Park, London. This is close to the total average monthly rainfall for July in London, with average rainfall for the month being 45mm (Guardian, 2021b). Several roads and underground stations in London were affected (Guardian, 2021a). The wettest area in London was St James’s Park which recorded 41.8mm of rainfall in a day. Bethersden in Kent received 48.5mm within one hour, between 3-4pm, while Ryde, on the Isle of Wight, received around 38.5mm (Guardian, 2021a). Torrential rain on 25 July 2021 deluged several locations around the south of England. Several vintage shops, bars and restaurants along Portobello Road were affected (Figure 5). Just five days later, on 17 July, 76mm of rain fell in 90 minutes, causing floods along Portobello Road, with flood levels reaching at least 0.45m (YouTube Guardian News, 2021). Kew, in south-west London, experienced 47.8mm of rainfall in a single hour, compared to an average monthly rainfall of 44.5mm, which makes it Kew’s wettest day since 6 July 1983 (Independent, 2021). The London Fire Brigade reported over 1,000 calls relating to flooding (BBC News, 2021). On 12 July, nearly a month's worth of rain fell in parts of London (BBC, 2021), resulting in 120 Kensington and Chelsea residents being evacuated from their homes (New York Times, 2021).īy lunchtime on the 12th, eight underground lines had been suspended and multiple underground stations had been closed, including Euston Station (Telegraph, 2021). To receive event response updates straight to your inbox, sign up to our mailing list at the end of the report. JBA’s Event Response team has investigated the meteorology of the events and discusses how such high levels of damage occurred, sometimes outside of areas that feature as high flood risk within broad scale nationwide flood maps.

Following several isolated days of intense rainfall across South-East England in July 2021, a number of flood claims were recorded, many of which occurred in London.

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