Winter may hold more sou'westers and cold snaps that may come as a shock given the past three have been record warm ones, a meteorologist says.

Temperatures around the country have plummeted this week, the Desert Road was closed for a time and down south snow blanketed the ground in parts of Southland.

With the winter months approaching after the wettest summer on record, NIWA meteorologist Chris Brandolino is among those studying the patterns to forecast what the next few months might deliver.

He told Morning Report there's likely to be more south-westerly winds and more frequent cold snaps than has been the custom of the previous three record warm winters.

"Even if we have a normally cold winter as it were, it'll probably be somewhat of a shock given the recent winters have been so darn warm."

While ski fields will welcome a return to a colder winter, they will need both cold and moisture for snow (supplemented by their snow-making machines).

The global climate is now moving into El Niño (when waters in the Pacific Ocean become much warmer than usual).

Currently, it's "in neutral" but as the El Niño takes hold it will drive more south-westerly winds which are not associated with moisture, so not favourable for the ski-fields, Chris says.

"It wouldn't be surprising to see kind of a drier lean as we work our way through the winter season."

It will be unlikely all the rainfall that has occurred this year will persist because La Niña, which has been influencing the weather for the last three years, has disappeared.

"So that climate driver which was helping to produce those events no longer exists."

In the short-term, however,Chris draws on Covid-19 to compare what has been happening with the latest bad weather, a sign of La Niña's long atmospheric tail.

When the weather is terrible it was like having Covid, it improves but like the virus' lingering symptoms, it produces a few more issues, including a low set to arrive late next week which could deliver "a quick burst of rain".

-RNZ.