“Winter is coming.”

That’s the warning from fire union officials who sounded the alarm Monday over what they say is a potentially deadly reduction in fire engine staffing due to migrant-fueled cuts to the department budget.

As part of Mayor Eric Adams’ latest budget reduction to cover the $12 billion price tag to care for tens of thousands of asylum seekers in NYC, the fire department has cut the so-called “fifth man” at 20 of the busiest engine companies around the city.

Uniformed Firefighters Association President Andrew Ansbro slammed the move, which went into effect over the weekend, telling The Post that having extra help can halve the time it takes to get water on a fire.

“Winter is coming and e-bike fires are on the rise,” Ansbro said Monday, explaining that the colder months have historically been the busiest times for the FDNY.

“If the NYPD told you gun crimes were on the rise and in the next sentence told you that they were cutting the gun unit, you would say ‘What are you doing!'” he exclaimed.

The mayor first pulled the fifth firefighter from the engine after taking over in 2022, but after the city saw one of the deadliest fires in NYC history just days into his tenure, Adams reversed course.

“If you would have had more hands in the stairwell, it would have led to less exposure and loss of life,” Ansbro said.

“They said then it would save $1 million per month but decided it wasn’t worth it,” he said.

The new cutbacks are expected to save about $8 million, according to union officials.

The Bronx blaze broke out in the Twin Park high-rise killing 17 people, including eight children. It was the deadliest fire in more than 30 years.

The fifth firefighter allows the engine company to respond more aggressively when responding to fires and significantly cuts down on the time to run hoses and get water pumping onto blazes.

An FDNY Engine Company is typically staffed with five firefighters and one officer.

The officer, who is a lieutenant or caption, works with the two firefighters operating as the nozzle workers.

Together, they operate the hose and spray the blaze with water. They are also the closest to the fire and danger.

A third firefighter operates as the door person, checking and opening all the doors from the street to the origin of the fire to clear a path for the hose.

The fourth firefighter works as the control person, checking for kinks and obstacles that may impede water flow through the hose.

The fifth firefighter is the motor pump operator. The MPO is usually a senior smoke-eater who drives the engine, connects to the hydrant and controls the water flow from the engine.

When there are only four firefighters, one person would do the job of both the door and control workers.

Without a fifth, firefighters might also have to take more defensive approaches while waiting for backup.

Union officials told The Post that proper staffing levels to allow for the quickest responses are more important than ever now with how fast-moving fires are when sparked by e-bike batters.

“During a fire, saving seconds save lives, and losing time costs lives,” the union wrote on social media over the weekend.

The city is allowed to cut the fifth man under a clause in the firefighters’ union contract that say the position can be eliminated whenever the number of firefighters out sick or injured rises above 7.5%. Currently, there are about 8% out.

Ansbro railed against the clause, saying it was calculated decades ago when FDNY staffing levels was vastly different.

“Of course, our leave numbers are up,” Ansbro snapped, adding that FDNY staffing has dwindled over the years, leading to more injuries among the overworked firefighters.

The union head said the engine staffing reduction has been available to City Hall for years, but former Mayor Bill de Blasio never pulled the trigger.

“In the face of significant fiscal challenges, this administration continues to balance the budget, just as the law requires, while simultaneously minimizing disruption to services,” said City Hall spokesperson Amaris Cockfield. “As a result of the lack of significant and timely support from Albany or Washington, D.C., every agency had to dig into their own budgets to find savings.”

“The mayor has been clear that he will never do anything to put public safety at risk, and this temporary change, representing a small fraction of our engine companies, will not affect response times whatsoever or derail the FDNY from this mission to respond quickly to fires,” she said.

The fifth firefighter is expected to be returned when the medical leave numbers drop, Cockfield added.

“This reduction of staffing will make it more difficult to fight fires in those affected neighborhoods,” the union wrote on Facebook over the week, noting the 20 engine companies will see reduced staffing, including East Village, Midtown, Midtown Harlem, Borough Park, Bed Stuy, East Flatbush and Jamaica/

“The staffing cuts made today WILL cause a delay of MINUTES not SECONDS, and the NYC budget will be balanced by putting the lives of NYC residents and the safety of NYC Firefighters on the table.”

With additional reporting by Juan Gonzalez