Transport for NSW has told drivers to expect delays and allow extra travel time while one of Australia's largest agricultural events takes place at a site off Henty-Cookardinia Road from September 17 to 19.

"Traffic will be heavier than usual along the Olympic Highway between Wagga and Henty, and on approach to the Henty-Cookardinia exit each day of the event," the agency stated.

"Motorists should expect delays and additional travel time."

The Henty Machinery Field Days gates will be open to the public from 8am to 5pm daily, with more than 800 exhibitors also attending the 105-hectare site.

Field Days chief executive Belinda Anderson has also reminded attendees and all drivers using the roads around Henty during the event to take care and be aware of changed traffic conditions.

READ MORE: Henty prepares for field days influx