Crews in St Helens were called out to just two deliberate fires over the Halloween weekend, the service has said.
Firefighters were called out to 38 deliberate secondary fire on Friday, October 30 and 31 across Merseyside.
People are urged not to supply young people with wood or combustible materials that could be used to build bonfires in the run up to Bonfire NightWatch Manager Ian Mullen
Of the incidents over the two days, there were 21 in Liverpool, 11 in Wirral, three in Knowsley, two in St Helens and one in Sefton.
Watch Manager Ian Mullen, Merseyside Fire and Rescue Service’s arson reduction co-ordinator, said: “People are advised that deliberately setting fires is arson. We work with Merseyside Police to identify those responsible and if caught they will be prosecuted.
“If a fire appliance is called out to a deliberate fire it may delay the response to another emergency.
“Bonfires and wheelie bin fires can easily get out of control, causing a danger to people.
“People are urged not to supply young people with wood or combustible materials that could be used to build bonfires in the run up to Bonfire Night.
“Residents are also urged to only put their wheelie bins out on the day of collection and to bring them in straight after. Wheelie bins should be stored away from windows and doors. Where possible bins should be locked away.”
To report an unlit bonfire or for free fire safety advice call Merseyside Fire & Rescue Service on 0800 731 5958. Outside office hours, please leave a message with your details and a contact number.