Updated Thursday 9am — Southern NZ has overnight lows close to (or at) freezing this Friday night / Saturday morning as spring ups and downs continue.

WeatherWatch.co.nz says the Southern Ocean is much more active this year and is contributing to the odd cold southerly into the country.

“We’re seeing short bursts of cold air due to a much stormier Southern Ocean this spring” says head forecaster Philip Duncan. “A colder southerly on Friday will be quickly followed by high pressure on Friday night/Saturday morning, allowing cold air to sink inland and temperatures to approach freezing for some”.

Mr Duncan says the stormy Southern Ocean weather looks set to cancel out some of the impacts of La Nina in southern NZ, bringing more cooler injections of air and wetter weather also.

The interactive Below Zero temperature map at WeatherWatch.co.nz is already showing the risk areas (in purple shading) – and this has expanded quite a bit in the past 24 hours.

Even some inland parts of Nelson and Marlborough may be down to just 2 or 3 degrees into Saturday morning.

For most it will be too mild for frosts, despite the low temperatures. But certainly northern Southland, parts of Central and western Otago and Canterbury’s high country do have some risk. The warm weather before hand will help lift soil temperatures further, with daytime highs in Southland in the low 20s for Thursday.

But we can’t rule out a light frost patch – or at least some ice on the roof of any vehicles parked outside at night. Any frosts will be light.

But it’s short lived. In fact after Saturday morning’s cold start, Saturday afternoon will see a warm nor’wester from Australia moving in and pushing daytime highs up several degrees higher than Friday. (With highs in Southland approaching 20 degrees).

Friday, Sunday and Monday all look cooler in the south as another stormy low tracks by to the south and south east.

Spring weather (the ups and downs) can continue in New Zealand through December too, although high pressure looks like it will bring some more settled weather by the end of next week.

Some Overnight Lows Friday Night/Saturday morning:
Lumsden: +2
Tekapo: +0
Balfour: +2
Alexandra: +3
Te Anau: +3
Twizel: +2
Queenstown: +2
Arrowtown: +3
Gore: +3
Dunedin: +5