The Professional Firefighters Union says staffing in Auckland has reached crisis point.
The union says over the weekend there were 23 gaps in firefighter coverage, including five fire trucks out of commission due to no staff and several more short-staffed.
The union's Auckland local secretary, Martin Campbell, said there has been a lack of investment over the past 10 to 15 years.
"Now unfortunately it's hitting rock bottom and it's becoming a crisis point, we've had no significant increase in the number of career firefighters in Auckland since the 1980s and early 90s, in fact Auckland is less than half the number of career firefighters per capita than the rest of New Zealand."
On Saturday in Tāmaki Makaurau, there were 98 firefighters on during the day, 20 per cent fewer than usual, looking after the region's 1.7 million people, Campbell said.
That created a massive risk both in terms of public safety and for the safety of firefighters, he said.
"If stations are unstaffed or closed down because we haven't got enough firefighters, other stations have to respond from longer and further away, it takes longer for Fire and Emergency to get fire trucks to emergency incidents."
Fewer staff also meant those firefighters who attended incidents were more likely to have to take more risks to get the job done, he said.
It was also a lot harder to find people wanting to take up the role of career firefighter, Campbell said, adding that the wage that career firefighters started on, particularly in their first four of five years in the role, was barely above the living wage.
Fire and Emergency says it can respond to emergencies
Fire and Emergency is defending firefighter coverage, and said it was currently negotiating with the union over the collective employment agreement.
Fire and Emergency region manager Ron Devlin said he wanted to reassure the community that the service had the capacity and planning in place to respond to emergencies.
"We have capacity built into our capability to allow for coverage on any given day should appliances be committed to large fires or when we routinely take trucks off service temporarily for several reasons - including training our people and maintaining our fleet," he said in a statement.
There are 70 fire stations across Tāmaki Makaurau crewed by volunteer and career firefighters.
Like many organisations Fire and Emergency has been impacted by staff absences due to Omicron but there are always contingency plans in place to enable to the organisation to respond to callouts, he said.
"Our career firefighters work an average 42 hours per week, before overtime, based on two-day shifts followed by two night shifts, and four days off. All firefighters who have completed their initial 12-week training course have the opportunity to earn significantly more than their base salary by undertaking additional or specialist duties and working overtime."
Fire and Emergency New Zealand recruited for career firefighters twice a year and it received applications from many quality candidates, he said.
"In fact, we are currently running an additional recruitment for Auckland only, which opened on 1 April and will close on 15 May, with the objective of filling an additional 15 to 20 roles."