Londoners have been left baffled over a mysterious 'black hole' that's appeared in the sky above the capital, reports Daily Mail.

Incredible photos shared online show ominous dark skies above the Houses of Parliament as dozens of Londoners questioned the unusual formation this morning. 

The strange meteorological occurrence is not a black hole as many social media users pondered, but Asperita clouds. These the dark and stormy clouds as common in the US and are typically seen following thunderstorms. Londoners online joked that the clouds may be a result of an alien invasion or an omen for President Trump's visit.

The clouds marked the start of the day as thunderstorms and rain battered Britain just days after it basked in the hottest day of the year.  A band of heavy showers are set to sweep across the country from today, with a yellow weather warning for rain and flooding in place for Northern Ireland. 

Met Office forecasters have warned nights may turn chillier as a system of low pressure makes its way across the UK over the next few days and into the weekend.