A small fire at the top of the Crown Range zig-zags, near Arrowtown, on Saturday night was started after someone dumped hot ashes in pine trees.
The Arrowtown Volunteer Fire Brigade was called to the vegetation fire at 8.44pm.
On arrival they found a fire about 20sq m in size burning under the trees.
Arrowtown Chief Fire Officer Murray Forward said two people decided to throw ashes from a fire box over a bank from a nearby property.
"They just threw them over the bank and away it went.
"If it was a couple of months either side, with that wee bit of a breeze that we had, we might have been stopping it in Wanaka."
The temperature at the time was about 3degC.
It took "a couple of hours" to fully extinguish the fire, which measured about 4m by 5m. Thermal imaging equipment was used to check for any other hot spots.
Mr Forward said fire ashes needed to be stored in a steel container for "five days, minimum", after which they should be watered and then disposed of "appropriately".
Meanwhile, a Fire Emergency New Zealand spokesman said the Frankton volunteer fire brigade was called to help secure a roof at Jack's Point yesterday morning.
The brigade was called at 11.16am after a "roof was lost overnight from a property".
"I assume that means blown off," the spokesman said.
The Frankton brigade used "a couple of ladders and some lines kit" to secure what was left, he said.
