An intensifying weather system will bring snow to low levels tomorrow evening and night, heavier in North Canterbury.

Blue Skies Weather & Climate Services said instability in a cold air mass will be triggered as the weather system moves over Canterbury during the night. 

For farmers:

For most of South and Mid Canterbury expect accumulations of 3-5cm above 400m, and 5-10cm above 500m, tomorrow evening.

Some light flurries are possible down to 200m on the western Plains.

In North Canterbury expect accumulations of 5-10cm above 300m tomorrow night and early Thursday, with 10-20cm possible above 500m by mid morning on Thursday.

Some light accumulations of a few cm are possible above 200m early Thursday morning, with flurries to sea level. 

A further low level snow event is possible on Monday, and a third event may develop at the end of next week.

For travellers:

Blue Skies Weather & Climate Services said light snowfalls are possible on southern passes late in the day tomorrow.

Moderate falls may cause disruption to Arthurs Pass and environs tomorrow night, and moderate to heavy falls look likely to cause disruption to the Lewis Pass tomorrow night and Thursday morning.

There is also a risk of some snowfalls on higher level roads through North Canterbury and the Kaikoura area early on Thursday morning, including State Highway 1. 

Elsewhere

Light snow falls to low levels, possibly near sea level, are expected during the afternoon and evening tomorrow in Otago and Southland. Snow accumulations are possible to moderate levels in the Nelson and Buller areas tomorrow night also.