The Met Office has warned of stormy weather on Sunday as the final day of Platinum Jubilee celebrations get under way.
Issuing a yellow warning for the south of England, Midlands and parts of the north., the Met Office said that Sunday may bring thunderstorms that could result in "fast flowing or deep floodwater, causing a danger to life."
The Met Office added that "flooding of homes and businesses could happen quickly, with damage to some buildings from floodwater, lightning strikes, hail or strong winds".
The national weather forecaster continued: "Where flooding or lightning strikes occur, there is a chance of delays and some cancellations to train and bus service.
"Spray and sudden flooding could lead to difficult driving conditions and some road closure.
"Power cuts might occur and other services to some homes and businesses could be lost."
In a tweet on Saturday evening, the Met Office advised party hosts to check the forecast ahead of time.
"If you're hosting or attending a street party, or doing something completely different, take a look at our 4cast, as once again there is quite a variety of weather on offer for Sunday," they said.
A Met Office spokesperson said:"Thunderstorms and areas of rain are expected to develop over parts of England and Wales during the early hours of Sunday.
“Torrential downpours are likely in a few places with parts of the Midlands, East Anglia and southeast England most at risk.
"Some places could see 15-20 mm in an hour, and perhaps up to 50 mm before storms fade, and hail may affect a few spots."
The events marking the Queen's Platinum Jubilee will come to an end on Sunday, with millions of people across the country planning celebratory street parties and outside lunches.
According to the Royal Family website, some 60,000 have registered to host official 'Big Jubilee Lunches' events, which include "world record attempts for the longest street party to back garden BBQ’s and everything in between".
More than 10 million people are expected to join in the celebrations on Sunday, with many having applied to their local council to close their road to traffic in order to set up large parties in the street.
Sunday will also see the final formal events of the celebrations, culminating in an extravagant Platinum Jubilee Pageant at Buckingham Palace.
According to the official event website, the Pageant "will combine street arts, theatre, music, circus, carnival and costume to celebrate Her Majesty’s unwavering duty, love of the natural world and dedication to the Commonwealth".
The Pageant is estimated to have cost approximately £15million.
