The motorway has been shut between J7 and J7 near Reigate in the clockwise direction. The source of what is amounting to huge delays is flash flooding caused by heavy rain. Images from the M25 show some cars stranded in the standing water, while queues are very heavy on approach to the flooding. The Met Office has forecast that there will be heavy rain and thunderstorms for most of the evening in the areas around London. The Met Office has issued yellow thunderstorm warnings for the next five days, with the potential of flash flooding or damage to buildings from lightning and hail.

Source: Daily Mirror August 13, 2020 16:13 UTC