Arsonists set fire to trees and wheelie bins at three different locations overnight.
A tree went up in flames in Biscay Way, Wath, Rotherham, at 7.40pm and a crew from Dearne Valley Fire Station was called out to deal with it.
A number of trees were also set alight in Elm Wood Avenue, Woodlands in Doncaster, at 8.45pm.
Adwick firefighters spent 30 minutes tackling the blaze.
A wheelie bin was pushed into a skate park and set on fire in Farm Road, Kendray, Barnsley, at 9.35pm.
Firefighters from Cudworth Fire Station used hose reels to extinguish the blaze.