The shop had been selling plenty of costumes, with vampires and zombies the most popular choices, she said.
Mrs Davy said decorations for houses were also selling fast, including skulls, spiders, pumpkins and babies' heads.
"It's great to see so many people getting into the spirit of Halloween. It's a lot of fun."
Shiffa Haiunani, owner of Kids Warehouse on Eruera St, said she expected an influx of people today.
"We've sold quite a lot of Halloween costumes so far, but normally there's an influx on the day," she said.
Angela Baker has been looking forward to celebrating Halloween with her children for weeks. She's been busy decorating her house, her front gate and fence and organising costumes for her kids, something that's become a tradition over the years.
She said she'll dress up and supervise her kids while they go trick or treating. Her husband will stay home with their younger kids to hand out treats, all dressed up, too.
The frenzy over 2013 film Frozen has seen it become the most searched costume idea.
The five most-searched-for Halloween costumes
1. Frozen characters
2. Zombie
3. Ninja
4. Pirate
5. Clown
Data from SLI System
Safety tips for trick-or-treaters
*Stay in well-lit areas.
*Be careful not to frighten elderly people.
*Don't enter any house, stay on the doorstep.
*Only go to where you or your friends know the residents.
*Always go trick-or-treating with an adult.
*Be visible.
*Stay with your friends.
*Don't knock on doors where there is a sign saying "No trick or treat here".
*Don't talk to strangers on the street.
*Understand what a prank is. Don't commit a crime thinking you will get away with it because it is Halloween.
For householders
*If there are any problems or incidents outside your house and you are concerned ring police.
*You can print a copy of the Trick or Treaters posters from www.police.govt.nz and display whichever side you would prefer in the window or on the front door.
- Neighbourhood Support Rotorua and Rotorua police.