"An unprecedented early start to summer saw fans, paddling pools and beach accessories fly off the shelves from the beginning of November," Epke said.
"Demand for these products continued throughout Christmas and New Year, particularly in the Wellington region - which experienced the largest sales growth for fans across the country, compared with last year," she said.
"While there is some stock of fans available in stores across the country, we'd recommend getting in very quickly."
MetService said temperatures were set to rise above 30C in many cities today with Masterton expected to reach 33C.
Hundreds of people have taken to Facebook to complain about the nationwide shortage, with several saying they had forked out up to $600 for fans at Noel Leeming after coming up empty at other retailers.
Natalie Crook said a family member had been told there were no fans in the Wellington region until a new shipment arrived.
Juliet Oates in Greymouth said unless people were willing to pay hundreds for a fan, they were out of luck.
"Unless you want to spend between $400 to 700 for a really flash one [there are none]. I've even ordered and paid twice for one online only to have my money refunded due to not being able to supply from Kmart and The Warehouse."
Trade Me spokesperson Logan Mudge said the recent hot spell had seen thousands of Kiwis heading to Trade Me for fans.
"Last week we saw more than 24,000 searches in ten days for fans, he said. "Sales are far exceeding last year when New Zealand's summer was a little less intense."
