THUNDERSTORMS are threatening to torpedo the star-studded Platinum Jubilee concert on Saturday.
The Met Office are mulling over plans to issue a weather warning amid concerns rain will pour down on the Party at the Palace.
As a host of famous faces gear up to give the performance of a lifetime, organisers are scrambling to ensure the stage is watertight.
Forecasters have warned heavy, possibly thundery, showers could put a dampener on celebrations in the capital, while lightning may strike too.
Patriots partying al fresco may have to rethink their plans amid concerns the entire historical weekend could be a washout.
The storm is predicted to hit some parts of England and London on Saturday evening - just as the open-air concert kicks off.
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But meteorologists are reluctant to bring in any official weather warnings over the monarch's momentous weekend just yet.
It seems history could be repeating itself after the heavens opened during Her Majesty's Diamond Jubilee in June 2012.
Millions of Brits still turned out in droves to celebrate - but were left soaked at the Flotilla tribute on the River Thames.
The Met is expected to review the situation on Friday morning, just over 24 hours before the likes of Alicia Keys and Diana Ross take to the stage.
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Up to 22,000 lucky Brits will be boogying at the royal household - but they may need to pack a waterproof too.
Met Office meteorologist Simon Partridge said the service is considering the weather warning for thunderstorms due to the volume of people expected in London.
He explained: "It's being monitored but at the moment there's not enough confidence to issue any warnings.
"But it's one that's going to be reviewed tomorrow morning as to whether or not we do require a thunderstorm warning, simply because of the number of people we're expecting in the capital on Saturday night, so that's one area of slight concern in terms of weather causing some issues for festivities."
And it's not just Londoners in the firing line for thunder - as the forecaster warned the weather could cause travel chaos.
Mr Partridge suggested it would impact visibility on the roads and largely increase travel times for drivers.
He said: "I suppose it would be advised to take care or, at the very least, to leave extra time for journeys.
"In those areas of rain, the visibility - because of the surface spray as well as just the rain on the road - will really mean you will have to reduce speeds.
"Certainly heavy rain with a risk of lightning and the usual associated risks there of some surface water issues, spray, poor visibility on the roads, and of course, if you are out, you are going to get wet."
The unfortunate weather could also clash with other key Jubilee events in the coming days.
The north-west is set to see outbreaks of rain into Thursday night, around the time Jubilee beacons will begin being lit across the UK.
Friday is predicted to see gorgeous 26C highs.
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But thunder, cloud and cool temperatures are expected further into the bumper Bank Holiday weekend.
Temperatures of around 20C are expected on Saturday, while the mercury drops on Sunday a few degrees further to 18C - with more rain.