Christchurch is set to bask in its warmest day of spring so far on Tuesday, with temperatures forecast to reach 27°C.

Gusty northwesterlies were expected to develop across the city, driving temperatures well above normal for this time of year.

Fire and Emergency New Zealand (Fenz) urged people to take extra care because of the increased fire risk.

MetService meteorologist Luis Fernandes said the forecast high was about 10°C above the average maximum temperature for Christchurch in mid-October.

"We've seen temperatures climbing into the low 20s on and off over the last couple of weeks. This will be the warmest day we've had over the course of the season," he said.

The hot spell would be short-lived however, with a front expected to bring rain from Wednesday.

"We're going to see wetter weather settling in during Wednesday and Thursday, and then temperatures will take quite a bit of a dive heading into the last couple of days of the week," Fernandes said.

Friday's high for Christchurch is just 11°C, with frosty mornings possible over the weekend.

"It is very typical of this time of the year to see this sort of flip-flop between much warmer weather and then much cooler weather. Spring is a transition season, so we're going to continue seeing stronger fronts moving through from time to time," Fernandes said.

Fenz Canterbury assistant district commander Des Irving urged people to not start fires in windy and hot conditions.

"If we do get the expected hot temperatures and strong winds it will certainly drive up the potential fire risk which would be a concern for us in Canterbury," he said.

"In October last year we had similar conditions in Kaikōura and we experienced runaway fires that destroyed a number of homes and dwellings. Those fires started primarily from previous burnt piles that the wind disturbed and pushed the embers around the town.

"If you've already burnt the day before and the wind gets up, go check that the fire is actually out. That may require you to rake over the ash pile and apply more water to fully extinguish the fire."

Irving advised people to use the Check It's Alright tool before lighting any outdoor fire.

Fenz was continuing to investigate the cause and origin of the Walter Peak fire near Queenstown.

The blaze on the southern shores of Lake Wakatipu started on October 6 and was contained two days later after scorching about 1350 hectares of land.

Fenz was investigating if there was any connection to a controlled burn carried out at Walter Peak High Country Farm on September 30.