All customers and stallholders, unless exempt, have to wear a mask.
Typically retailers don't have to ask for vaccine passes upon entry but they may choose to if they want.
Whanganui River Markets organiser Annette Main said they were doing their best to get the market back to its place as an important "community gathering place".
But there was a balancing act between hosting the event and ensuring safety.
"It's a dilemma for us because we know how popular this market is as a community gathering place, as a place our community loves to go.
"And we know that's really important right now for our community."
She said organisers got criticism last week for asking people to show their vaccine passes and she was sure they would get criticism for not asking for them this weekend.
"I'm sure we'll get flak either way."
Main said she and other organisers had so far erred on the side of caution about how to hold the market because of low Covid-19 vaccination rates in the Whanganui area.
But she was pleased the rate had increased and felt confident to open up to more stalls.
The 1m distancing rule would govern the number of people allowed onsite.
"If we need to, we will introduce the one in, one out policy. We will be watching that very closely."
People who buy food at the market to eat it will have to go to the riverbank area outside the market.
Main said the market would cancel "at the last minute" if they had to.
"If we have to cancel at the last minute because we receive advice that holding this is not the [safest] thing to do, we will cancel it."