Cuts to the Merseyside Fire and Rescue Service have "compromised" the way it responds to emergencies, a new report has said.
Merseyside Fire and Rescue Authority said it "reluctantly accepted" that, to make savings, it had to cut immediate overnight fire cover at six stations.
Its Service Delivery Plan for 2018-2019 also stated the authority faces "significant" grant cuts up to 2019/20.
The Home Office said the authority had enough resources.
The report said stations in the Crosby and Eccleston areas will be fully staffed during a 12-hour day shift but at night crews will be at home, available to return to work within 30 minutes.
It added the response to an emergency will be provided "within our standard of 10 minutes from stations that are fully staffed at night."
Also affected are St Helens, Newton-le-Willows, Wallasey and Liverpool City fire stations.
The authority said cutting night cover was "a better option than closing fire stations".
But it added: "There is no doubt that the scale of the cuts we have been required to make is now beginning to compromise the way we respond to emergency incidents."
The Fire Brigades Union (FBU) said the cuts were a "step too far".
It said it was deeply concerned about Eccleston where only one fire appliance coves the areas of Eccleston, St Helens and Newton le Willows from 22:00 to 08:30.
The union said it did not believe the service had the resources to cope with a Grenfell-type incident adding the effects "could be catastrophic".
The FBU said the fire which gutted the Liverpool Echo Arena car park on New Year's Eve confirmed its concerns, adding the service did not have the necessary resources to deal with an incident which was a "much smaller scale than Grenfell Tower."
The fire authority said the Grenfell disaster resulted in "significant attention being placed on legislative fire safety" while the outcomes of the Echo Arena fire "will impact" on the service in years to come.
A Home Office spokesman said: "Merseyside Fire and Rescue Service will receive a core spending power of £60.1 million in 2018-19 - an increase of 0.9% compared with 2017/18.
"In March 2017, Merseyside Fire and Rescue Service held £31.9 million of non-ringfenced reserves, which is equivalent to 62% of their net expenditure."