A severe weather alert has been issued throughout the region.
The meteorological service’s yellow alert for thunderstorms will remain active between 2am and 8am on Thursday, August 27.
The warning applies to both East and West Sussex areas.
Members of the public have been advised to anticipate potential disruption stemming from the conditions, including flooding and electrical storms.
Transport services may experience delays or cancellations, while electricity supplies could be affected by the severe weather.
Individuals residing in areas susceptible to rapid flooding have been encouraged to prepare an emergency plan.
Motorists have been urged to verify road conditions prior to setting off and to modify journeys as required.
According to meteorological projections, a band of thundery conditions and substantial rainfall will advance northward into the southeast of England during the later hours of Wednesday and into Thursday morning.
Hourly rainfall totals of 20 to 30 millimetres are possible in some localised areas, with widespread accumulations of 30 to 40 millimetres expected over a six-hour period.
A small number of locations may receive in excess of 50 millimetres within three hours.
Electrical discharges and hail measuring one to two centimetres in diameter are also expected to pose risks, alongside the potential for powerful wind gusts in certain areas.
The advisory follows an extended spell of dry and warm conditions, which earlier this year prompted an uncommon red extreme heat warning for the region.
