Bus services on two major routes through Northampton will be diverted to allow the carnival parade to pass.
Northampton Carnival Day is on Saturday at Abington Park, meaning Wellingborough Road buses will need to be diverted from about 1pm.
The parade returns via Kettering Road, so buses will also be diverted from around 3pm hours.
Normal service is due to be resumed by 5pm, possibly earlier.
The carnival will return to Abington Park for the first time in nearly 20 years, in a move which will see its 1,000-strong parade head through more residential areas.
There will be more than 30 parade floats heading along Wellingborough Road, before heading into the town centre.
On its return journey to Abington Park the parade will pass through residential areas such as Clarke Road and Wantage Road.