Yesterday's fire near Pines Beach, north of Christchurch, may have been started by the same person who started a series of fires last year, the Fire Service says.
The fire began at about 2.30am, and ended up engulfing up to six hectares of forest.
More than 10 crews tackled the fire and a helicopter with a monsoon bucket went to the scene.
Principal officer for the Waimakariri District Council's Rural Fire Authority, Tim Sheppard, said it may be connected to some suspicious fires lit in the area last year.
"Exactly the same spot as the suspicious fires last year. I though we'd got away with it this year, you know this is the first one we've had down there. The same MO so I'm guessing that, yes, it is."
Tim Sheppard said the police were investigating the cause.
He expected his team would need to continue monitoring the site for up to a week.