Essential road repairs will begin at Peacehaven and Telscombe Cliffs later this month.
Night-time carriageway patching and joint repairs will start on the A259 South Coast Road on Monday, July 12 and continue until Friday, July 30.
Between July 12 and July 21, the A259 at Peacehaven will be closed from Sunview Avenue to just past The Highway between 8pm and 6am each night.
In addition between July 12 and July 30, temporary traffic lights will be in place on the A259 at Telscombe Cliffs from the junction with Telscombe Cliff Way to just before the junction with Hamsey Road between 8pm and 6am each night.
When the road is closed at Peacehaven, traffic will be diverted via Rottingdean High Street, Falmer Road, A27, A26, A259 Newhaven and vice versa.
Access for residents will be maintained where possible but due to the nature of the work taking place there may be delays and the diversion route may need to be taken at times. Pedestrian access will be maintained.
Bus routes will also be affected by the road closures and people are advised to check with their bus company or visit www.buses.co.uk for information on changes to services.
Karl Taylor, head of operations at East Sussex County Council, said: “We appreciate the night-time roadworks on the South Coast Road at Peacehaven and Telscombe Cliffs will cause some disruption to road users and residents.
“We would urge people to plan ahead if they need to use this road during the three weeks when the work is taking place.
“We apologise for any inconvenience caused.”
Details of this and all forthcoming roadworks are available on the East Sussex Highways website at www.eastsussexhighways.com