Police are advising motorists and visitors to Wickham Horse Fair on Monday 21 May to allow more time for their journeys.
The fair takes place in Wickham Square, which will be closed to traffic from noon on Sunday 20 May until 8pm on Monday.
The A334 will be closed between the traffic signals at Blind Lane and the roundabout junction of the A32 from 5am to 8pm on Monday.
Arrangements have been made for horse boxes to be parked on the east side of the A334 between the north end of the Square and the junction at Blind Lane and Titchfield Lane.
Any vehicle parked in an unauthorised place will be towed away.
Signage has been placed along the route to highlight the closures. Motorists not attending the fair may wish to consider alternative routes around Wickham.
A dedicated emergency telephone number has been set up for residents in the roads where access to their properties is affected. They have been contacted directly about this.
A spokesman for the Hampshire Constabulary said:
“Wickham Horse Fair has a long history and is expected to attract over a thousand visitors this year.
“We have been working closely with local authority partners and businesses to help ensure a safe environment for visitors and residents at the event.
“If you are planning to attend, you should familiarise yourself with road closures and parking arrangements. These are put in place to minimise disruption and inconvenience to local people and motorists.
“Officers in high visibility uniform will be available throughout the event to respond to any issues that may arise.”