It’ll be warm, but it might be wet

It won’t be a white Christmas in Christchurch, but it could be a wet one.

Forecasters Canterbury Weather Updates and MetService both warn possible thunderstorms, heavy rain and hail are set to plague the region until tomorrow. The chance of a small localised tornado and severe downpours in North Otago and Canterbury is unlikely, but totally not off the cards.

The wet weather should mostly clear by December 25 for balmy Christmas conditions but afternoon rain was ‘‘certainly possible,’’ MetService meteorologist James Millward said.

‘‘There’s still a bit of uncertainty about rain on that day and some models are showing it over Christchurch in the afternoon.

‘‘[A sunny day] could still happen but odds are they’ll be clouds and possible rain. We would expect the models to crystallise over the weekend but some are looking pessimistic over Christchurch.’’

Experts agree that Tuesday’s weather will likely be warm, with the temperature set to reach 23 degrees Celsius in Christchurch. The weekend’s rain in the Garden City should pass by tomorrow afternoon, but models are divided on the possibility it returning on Christmas Day afternoon.

Canterbury Weather Updates is forecasting high intensity rain, and snow to 1200m with large hail and thunderstorms across the Canterbury Plains today.

Over the South Island, showers are expected with the passage of a front, possibly becoming thundery. Thunderstorms about North Otago, Canterbury, Marlborough and Nelson could bring hail, and heavy rain of 10 to 25 millimetres.

In North Otago and Canterbury, south of Christchurch, localised downpours could bring 25 to 40mm per hour and hail greater than 20mm in diameter.

Showers will dominate today and tomorrow in Christchurch, Ashburton, Dunedin, Blenheim, Nelson and on the West Coast.

Research by National Institute of Water and Atmospheric Research meteorologist Ben Noll found that historically, Christchurch and Wellington were the centres most likely to enjoy a dry Christmas Day.

Of the past 30 Christmases, Christchurch has experienced just four wet days but also holds the record for the wettest Christmas Day on record of any main centre. Back in 1909, a whopping 59.7mm fell.

For the big day, all southern regions were set to hit the mid-20s.

Dunedin will be fine with northeast breezes and a high of 23C, Kaikora will reach 22C, as will Nelson. Blenheim will be the pick of the bunch on 24C. On the West Coast, Westport, Hokitika and Greymouth should reach 22C.