The quarantine and vet rooms will be open for people to have a look, and visitors will get the chance to learn more about how the centre operates.
Mr Auger said "microchipping for cheap" would be running, and local vets and the radio would be present. There will be a petting zoo, face-painting, a bouncy castle and a sausage sizzle, among other things.
Staff would also answer questions about their work in dealing with complaints or rescuing animals.
"It's about raising awareness ... what we do, what we promote." A gold-coin entry will help fundraise for the SPCA.
Mr Auger said open days had been held at other SPCAs and they were "obviously a lot of fun". The Wanganui SPCA is at 134 London St.