The Warehouse has ordered more fans as very limited numbers are available at its stores in Whangarei, Dargaville, Kaikohe, Waipapa and Kaitaia.
"An earlier than usual start to summer saw fans flying off the shelves from early November and this continued right throughout Christmas and New Year," Jenny Epke, general manager for general merchandise, said.
She said the company has sold more than double the number of fans, pools and water sports' equipment this summer compared to last year, although she refused to say how many as that information was commercially sensitive.
Whangarei-based Chilltech refrigeration and airconditioning engineers has experienced a high demand, not only for cooling systems, but for repair and maintenance of refrigerators as humidity put a lot of strain on them.
Sales manager Tim Bird said the company was supplying hats and sunscreens to employees installing air condition units and undertaking similar work where part of the job entailed getting into ceilings and under houses.
The heat in ceilings from mid-morning to midday could be as high as 50C, he said.
"We start work early and try to get the ceiling portion done before the heat kicks in. That leaves outside work but we still have to do that in the sun.''
Mr Bird said the heat in recent times had been worse with the warmer than normal December last year.
"Usually the more humid months for us are February and March so it'll be interesting to see what unfolds weatherwise in those months this year."
Mr Bird said there has been an increase, not just in the number of people inquiring about air conditioning units, but in their installation as well.
Rose Davison, of Smart Energy Solutions, said installation work during summer in Northland was scheduled for earlier in the day when temperatures were not as extreme.
The importance of installers keeping themselves hydrated to ensure they were not at risk was always emphasised, she said.
Ms Davison said many people who thought about DIY installation of insulation underestimated the working conditions and hazards such work posed apart from the extreme heat.
The heat is not only affecting people but animals, with the Bay of Islands SPCA having to attend several reports of dogs left inside vehicles.
A deep low will lower temperatures for a week from today but the humidity will linger a little longer.
MetService says daytime temperatures will be between 22C and 25C for the next week, but overnight temperatures will drop to between 15C and 16C during the same period. Overnight lows in recent days have been between 17C and 20C.
Northland has had 13 days in a row where the official daily high has been 25C or above.
However, with the official temperature recorded at Whangarei Airport, the temperature inland is always higher. On January 25 the MetService's official high for Whangarei was 29.1C, but it also recorded 33.1C at its weather station in Whau Valley.
