Heavy rain will spread across northeast England and east Wales until Thursday.
The Met Office’s yellow rain warning covers much of southern and eastern England from midnight Wednesday until Thursday, and until 9pm BST.
Rainfall totals early Thursday morning could be 20 to 30 mm (about 1 inch), and in some places 30 to 50 mm (up to 2 inches).
There is a small chance that some places will exceed this, most likely in Devon, Cornwall through to the East Midlands, Lincolnshire, Humberside and East Anglia.
Localized flooding and some transportation disruptions are possible.
The wind will also strengthen for a time in the early hours in Kent and Sussex, with a Met Office yellow warning in force across the east of England from 03:00 Thursday until 23:59 BST.
While conditions may temporarily improve, winds will pick up again during the afternoon.
There is an additional yellow warning covering west Wales and south west England from 06:00 to 15:00 BST.
Very strong northwesterly winds gusting to 70 to 90 km/h (45 to 55 mph) are possible in both areas, while locally they may reach 97 km/h (60 mph) in exposed coastal areas.
While there is still some uncertainty over the intensity of this weather system, the Met Office warns that there is a possibility of gusts of up to 120 km/h (75 mph) for a small period of time later on Thursday morning on the North Sea coast.
These wind speeds have the potential to down trees or their branches, cause travel disruptions, and even cause power outages.
