"Back in the old days that was like a cut off point for food gathering and stuff, and then you were into your three months of winter," Rewiti said.
As well as learning about the significance of Puanga, visitors will hear a tale from Rewiti herself - that of the taniwha Tutaeporoporo.
Local artist Cecilia Kumeroa has made shadow puppets especially for the story.
"It's the most well-known local legend," Rewiti said.
"The carvings that actually tell the story are on Putiki Marae."
The museum will be joined by the Sarjeant Gallery, Whanganui Astronomical Society, and the Department of Conservation.
"Sietske Jansma from the Sarjeant be making night-time bird masks. There's lots of little activities all around the place," Rewiti said.
"On top of that there will be a sausage sizzle to warm everyone up."
The Whanganui Regional Museum's Puanga evening is on Friday, June 9 from 5pm to 8pm.
It is suitable for children aged 5 to 12. Entry is a $2 donation. Numbers will be limited on Friday night, so booking in advance is essential. Phone 06 349 1110 to reserve your place.