Barry Mason, assistant director of highways at North Yorkshire Council, said visitors and those using main roads in the area should allow extra time for their journeys.
“With hot weather forecast and high traffic levels, congestion and delays may increase,” he said.
Wetherby Road will have one-way traffic towards the showground from the Kestrel roundabout to the Rudding Lane junction from 06.30 on show days, organizers said.
The A658 from Thistle Hill junction to Kestrel roundabout will also be one way, but only in the mornings.
The route between Sainsbury’s and Kestrel roundabout will be diverted this afternoon until 9pm to accommodate traffic leaving Harrogate.
The council said temporary traffic lights will also be installed on the A59 Kex Gill and will be closely monitored throughout the week.
“Please be patient while traveling,” Mason added.
“As always, please check traffic and travel information before departure and consider alternative routes if necessary.”