It's called the 4th annual  Sleigh Day Play Day and it's set to happen in Union Gap on Saturday, January 18 from 11:00 a.m. to 2:00 p.m.
According to a news release from Union Gap the Sleigh Day Play Day is a fundraiser for the Central Washington Agricultural Museum.
Officials say if there's snow you'll be able to enjoy a ride on horse drawn sleighs but if there's no snow, the horses are hooked up to wagons and you enjoy a wagon ride on the museum grounds. The museum is taking donations for the rides of  $5/person or $20/family. The news release says the donation will include hot cocoa/cider, one s’more kit per person, selfie photo station plus a tram ride to and from your vehicle. There is food for purchase during the event as well. Several of the museum exhibits and the Olde Yakima Letterpress Museum will be open and you are free to tour at no charge.

"The proceeds from the event help the Horse~n~Harness Group and the Central Washington Agricultural Museum with events, equipment cost and more throughout the year. The Horse~n~Harness Group has members from throughout the state who volunteer their time and horses for numerous events. The group gives demonstrations of antique farm equipment powered by horses at museum shows, they host Agri-Copia in the fall, they provide carriage rides for our grand marshalls during parades and there are even Driving Clinics to teach the art of driving horses in harness."