The warning is in place between 12pm and midnight today (Tuesday).
It stretches down the east coast of the UK, taking in Aberdeen and Edinburgh as well as Newcastle, Hull and parts of north London.
Although the hour-by-hour forecast shows no signs of rain for the Capital, the warning has been issued by experts at the Met Office.
Here's what the Met Office say to expect:
- There is a small chance that homes and businesses could be flooded quickly, with damage to some buildings from floodwater, lightning strikes, hail or strong winds
- There is a small chance of fast flowing or deep floodwater causing danger to life and there is a small chance that some communities become cut off by flooded roads
- Where flooding or lightning strikes occur, there is a chance of delays and some cancellations to train and bus services
- There is a slight chance that power cuts could occur and other services to some homes and businesses could be lost
- Spray and sudden flooding could lead to difficult driving conditions and some road closures
A spokesperson for the Met Office said: "Although some places will miss them, heavy showers and thunderstorms will break out in some areas this afternoon.
"Where thunderstorms do occur, torrential rain and frequent lightning is expected as well as a chance of gusty winds and hail here and there.
"A few spots could see as much as 30 mm rain in an hour and 40 to 60 mm rain in two or three hours."