We knew it was really, really cold and official records confirm it.

Last month was the coldest June since 1972 - in parts of the South Island it was the coldest in half a century.

The month also threw everything at us weatherwise: gale-force winds, flooding and even a tornado.

The only surprise in the latest National Institute of Water and Atmospheric Research (Niwa) figures was that Auckland had its sunniest June.

The big chill that gripped the country last month gave Tara Hills near Omarama minus 14C on the 14th, the lowest temperature since records began in 1950. Fairlie equalled its lowest June temperature, minus 14C. Its records go back as far as 1931.

The North Island was up to 2C below normal for the month and the South Island up to 1.5C.

And the country gobbled electricity to a corresponding degree, sending power records tumbling.

Demand reached 6748MW last Thursday, breaking two records set the previous fortnight and up 3.6 percent on the previous nationwide peak of 6513MW set in August, 2004.

"From the 11th of June, temperatures plummeted so the drop between May and June was very noticeable," said Niwa senior climate scientist Dr Jim Salinger. "The South Island had at least nine days where minus 10C or lower was recorded."

The two big weather events for the month were the snowstorm which blasted South Canterbury and North Otago on June 11-12 - Auckland was battered by high winds and rain on the 12th which cut power to the CBD for around eight hours - and the snowstorm that hit the central and eastern North Island on 20-22 June.

In between, there was flooding and a tornado near Greymouth and gale-force winds - a gust of 146km/h was recorded near Mt Kaukau near Wellington - on June 11 with another breezy blast hitting the North Island on June 19, bringing down trees in Tauranga and damaging powerlines in Taranaki, Bay of Plenty and Gisborne.

But the sun shone to record-breaking levels in Dargaville, Auckland, Hamilton, Stratford and Dunedin because of an unusually high number of high pressure systems moving over the country from the west which brought clear skies and polar-tinged southerlies straight from Antarctica.

"The thing about winters in the last decade has been that they have been warm and suddenly we got a cold month," Dr Salinger said.

Niwa would release its three-monthly outlook on Wednesday, showing whether predictions of normal to slightly above normal temperatures for this winter still held, he said.

National grid operator Transpower said demand for electricity through June was "successfully managed" with all major generators making supply available at peak times.

Holiday weather bad unless you want snow

The beginning of the school holidays brings bad news on the weather front - unless you are headed to the ski slopes.

A messy trough of low pressure is expected to spread over much of the country from today, with an associated cold front beginning its sweep up both islands and yet another cold, southerly change arriving in its wake.

Snow is forecast to sea level in Southland, Otago and Canterbury with MetService predicting snow to 100m on the Kaikoura coast. However, the snow was not expected at the kinds of depths seen during last month's snowstorm that cut power to hundreds of homes Canterbury and North Otago.

Tomorrow, the front is forecast to move over the North Island, with snow possible about the ranges and affecting roads at higher altitudes including the Desert Road.

Very cold southerlies grip the South Island with sleet and snow forecast to 300m in the south and east.

Gisborne and Hawkes Bay will get mostly fine or cloudy weather today. The rest can expect rain to spread from the west after a fine start with cold southeasterlies strengthening in the south and east.

Towards evening, isolated thunderstorms are possible for northern Taranaki and north of Hamilton.

On Wednesday, showers stick around for Wellington but should clear elsewhere and cold southeasterly winds should ease as a ridge of high pressure spreads over the country.

By Thursday, it's expected to be fine in most places but cold - with frosts.

"There should be a couple of nice days later in the week but that's pretty much about it at the moment," said MetService forecaster Leigh Couper.

By Friday, the end of the first week of holidays, showers develop in the west of the South Island.

Another cold front will begin moving up from the South Island late this week.

Skifield operators in both islands report a bumper start to the season with one of the best snow bases in recent memory.