The Met Office said it recommended people not to shelter underneath trees and instead use a safe, enclosed shelter, such as a car.
It added that driving conditions might become more difficult due to spray and possible flooding.
Some public transport services could also be affected by the weather conditions.
People are advised to prepare an emergency flood kit, if they know they are in an area that is prone to flooding.
As well as covering the South East, the warning covers much of England and Scotland, including places such as Manchester, Glasgow, Birmingham and Newcastle.
A full weather forecast for where you live can be seen on the BBC Weather website or app.