The Met Office has issued a 28-hour weather warning for London as the capital faces a deluge of rain towards the end of the week.
The warning covers the whole of the south of England, including London, and lasts from 2am on Thursday to 6am on Friday.
The alert, issued on Wednesday morning, warns of the possibility of travel disruption.
A Met Office spokesperson said: “Flooding of a few homes and businesses is possible. Bus and train services probably affected with journey times taking longer.
“Spray and flooding on roads probably making journey times longer.”
The forecaster has advised anyone driving tomorrow to slow down as soon as “it’s time for your wipers”.
People should also avoid starting their journey during heavy downpours and increase their following gap if they are already driving when it hits.
Rain is expected to move southwest on Wednesday night before it pushes northwards on Thursday and decreases through the day.
Although it will be less wet over the weekend, conditions are set to be “largely cloudy with some rain in the south”.
The Met Office has also issued amber weather warnings for snow for parts of northern England and North Wales on Thursday.
Up to 25cm of snow is forecast across the Peak District and the southern Pennines, with a warning in force from noon until 6pm.
A separate warning for snow and ice is in place between 8am and 3pm across North Wales and Shropshire.
The Met Office said an amber warning means travel delays on roads were likely; public transport vehicles and cars could be stranded; power cuts were possible; rail and air travel delays were likely and rural communities stood a "good chance" of being cut off temporarily.
In the area covered by the snow and ice warning, the Met Office said untreated pavements and cycle paths could be impassable.
