FIREFIGHTERS will today monitor hot spots to prevent a flare up from a blaze that threatened properties at McLaren Flat.

Up to 10 properties were at risk at the height of the fire, which burned about 35ha of scrub between Knots Hill Rd and Toop Hill Rd after starting about 6pm yesterday, AdelaideNow reports.

Police say the fire was deliberately lit.

A Country Fire Service spokesman said 60 firefighters would be on the scene today.

"Crews have done a fantastic job overnight working on mopping up and blacking the fire out," he said.

"There is no active fire there (but) there are going to be a number of hot spots within the fire ground."

The CFS sent 135 firefighters, 23 tankers and three bulk water carriers to the scene to battle the fire yesterday.

The spokesman said crews would monitor the fire ground over the next few days.

Yesterday's fire follows three in the nearby Blewitt Springs and McLaren Vale since November 11 that police have attributed to arson.

Earlier this month, police appealed for help to find an arsonist believed responsible for the fires, which have raised concerns within the local community of a serial firebug.

Read more at AdelaideNow.