The fire near Hanmer Springs is under control, but firefighters are still working to dampen hotspots.
The scrub fire covered 60 hectares and closed the main route from Christchurch to Picton yesterday.
It burned along both sides of State Highway 7 between Culverden and Hanmer Springs.
Fire crews were under pressure to "lock down" the large scrub fire before north-westerly winds hit the area tomorrow.
Southern district shift manager Andrew Norris said 25 firefighters remained at the scene.
SH7 was open with a reduced speed of 30km/h around the affected area.
Hurunui District Council principal rural fire officer Allan Grigg said firefighters had today to make headway in putting out the fire before the hot, dry winds hit.
"We're almost guaranteed to get flare-ups tomorrow so we want to be in a position to control those," Mr Griggs told Morning Report.
"One of the problems we've got in the Hamner Basin is that it's a valley system ... so it's very, very hard to predict the winds. They tend to come from all angles and different strengths."
Helicopter pilots were on standby this morning in case monsoon buckets were needed.
Eleven people left their homes yesterday when the blaze flared up. The stayed with friends and family overnight.
Cordons were lifted at 8pm and the road reopened about 9pm.
Ground crews were in the area overnight making sure the blaze did not flare up near people's homes.
The Fire Service said it would take will take four or five days to completely extinguish the fire.
It was not yet known what started the fire, Mr Grigg said.