Forget summer, winter is in charge briefly across the South Island today with snow falling and settling across some parts of the Deep South just days away from February, traditionally the hottest time of the year.

WeatherWatch.co.nz says snow is falling at Lake Mahinerangi, 35kms west of Dunedin according reader Pieter Du Toit. (see photo)

It was a cold start across much of the South Island this morning too, with Christchurch on just 4 degrees overnight and some inland areas falling closer to freezing as the wintry snap moved through, as predicted at the start of the week by WeatherWatch.co.nz forecasters.

The cold change reached Blenheim around 7am dropping the temperature from 18 degrees at 5am to 9 degrees at 7am.

Kaikoura went from 17 degrees at 2am to 6 degrees at 5am while Timaru fell to only 3 degrees overnight.  Yesterday Timaru had a high of 27 degrees and Christchurch reached 29 thanks to the nor’wester ahead of the southerly.

WeatherWatch.co.nz says the southerly has also reached Wellington this morning and will continue to head north today, reaching Auckland and Northland this afternoon and evening.

Head weather analyst Philip Duncan says the reason behind the cold snap might surprise you.

“We usually think of highs, or anticyclones, as our summer friends that bring hot, sunny, beach weather – but the truth is that a high can also contribute significantly to cold snaps and this is what we’re seeing today”

Mr Duncan says without the huge high back in August, New Zealand would’ve missed out on the big Antarctic cold snap.  “These big highs line up near Tasmania and if they change their shape from being wide east to west to instead being tall south to north it can dredge up very cold air from the Southern Ocean, just like we’re seeing today”.

But summer returns this weekend.

“The good thing about a high that creates a cold southerly like this is that it then comes in the next day and pushes the bad stuff out east over the Pacific Ocean.  This weekend we’ll see a high rolling in bringing clear skies and lighter winds, but it will be cold to start with”.

WeatherWatch.co.nz says some inland frosts may be possible in the South Island tonight while many parts of the North Island will drop to single digits or very low double digits on Saturday night.

Sunday and Monday look warmer in a number of areas.

– Image / Snow falls at Lake Mahinerangi this morning, Pieter Du Toit

– WeatherWatch.co.nz

What are conditions like where you are?  Post a comment below!