Wairarapa Racing Club are also holding a race day at Tauherenikau Racecourse, near Featherston, tomorrow.
Secretary Ginni Thurston said they already had pre-bookings. "We've got huge amounts of entertainment for the children and live music, so it's a really good day out. It's not just about racing."
Tickets are $15 per adult and under 18s are free. Gates open at 9.30am and the first race is at 1.10pm.
The Friends of Cobblestones have organised a market day in the grounds of Cobblestones Museum, Greytown.
Vice-chair Linda Kirkland said any funds raised would go towards the beautification of the museum. "It's just a small market at this stage, featuring high quality crafts, produce and art."
The market will run from 10am until 1pm, and they hope to make it more regular throughout summer in future.
In Carterton, a Waitangi Day exhibition will be held in the Carterton Events Centre foyer from 10am until 4pm.
Wairarapa beaches were also expected to be busy and lifeguards will also on patrol at Riversdale Beach.
MetService has predicted the weather will be sunny with a high of 20C.
Meteorologist Daniel Corbett said the air will feel cooler and fresher than last week's record-breaking temperatures. "By the afternoon, it's a great looking day."
To be part of the Cobblestones Museum market day, contact Linda Kirkland on kirkland.linda1@gmail.com.