Weather: 'Extreme' fire danger for New Zealand as temperatures set to reach high 30s

Firefighters are urging Kiwis to be extra-careful as parts of the country are tinder-dry.

Hot air is blowing across from Australia, where it's already caused havoc. Out-of-control bush fires are currently tearing through Tasmania - and there are fears we could be next.

Temperatures are expected to push right into the high 30degCs next week, creating an extreme fire danger.

"You only need a few days of hot weather, which we're going to get, and the fire conditions can very quickly become extreme," Fire Risk Management principal advisor Michael Balmer says.

Firefighters are particularly worried about Canterbury, Marlborough and Northland.

The green grass in the undergrowth has been growing strongly all spring thanks to the rain - but now that it's summer, all that it needs is a few days of hot weather to dry out completely and become an extreme fire risk.

In Central Otago, the landscape is parched and about to get worse.

"It's dangerous, it's everywhere, if you look right down the valley there's so much grass and now it's all drying off," says resident Shelley West.

MetService warns there's no relief for the worst affected areas.

"It's going to remain this way for a number of days yet, we're going to see cloudy humid conditions in the west and some very hot dry conditions in the east," says MetService severe weather forecaster Peter Little.

As a result, some activities may just need to be postponed.

"If you're in a rural area, mowing lawns in the afternoon, in the hottest part of the day, if the blades hit a stone that causes a spark and pretty soon you've got a fire," Mr Balmer says.

The heatwave is already making its mark, and it's set to scorch New Zealand.