Britain could face one of the wettest summers on record with the Met Office reportedly warning nearly six weeks of rain could fall in just three months.
The forecaster is said to have told the Government and transport chiefs that there could be wet conditions throughout June and August.
In the same period last year, at least 2.5mm of rain fell on 40 separate days and this summer could see at least 50 damp days, according to the Sun.
It could be the wettest summer since 1912 if rain falls on more than 55 days.
Major events such as the Trooping of the Colour, Royal Ascot, Wimbledon, the Formula 1 British Grand Prix and Glastonbury could all be disrupted by the weather.
The Met Office long-range forecast said: “The chances of a wetter-than-average period are higher than a drier-than-average one.
“Rainfall at this time of year has a greater risk of localised heavy downpours and thunderstorms.”
The forecaster has predicted over eight hours of rain throughout Tuesday in London, with heavy showers also expected on Thursday and Friday.
The Met Office warned there could be “prolonged and thundery” conditions in London and the South East of England throughout Thursday although the showers will be less frequent on Friday and Saturday.
London has had a largely wet year, with the south of England experiencing its wettest February since 1836, according to Met Office data.
With the naming of Storm Kathleen, in April, the letter K was reached for only the second time since the annual storm alphabet was established in 2015.