A cold snap is expected to move over the country towards the end of the week, but temperatures are expected to remain the same in the Bay of Plenty.

WeatherWatch.co.nz says temperatures will be a few degrees colder in some areas than the current south west change.

Last week New Zealand's weather was dominated by a mostly northerly flow - unusual for around the equinox - now it's turned south westerly bringing heavy showers, squalls and a noticeable drop in temperatures, says head weather analyst Philip Duncan.

'We have a high over Tasmania and a low south east of New Zealand – it's the perfect set up to drive in wintry southerlies.”

Philip says strong to gale force south west winds are predicted in exposed areas - with blustery warm winds Friday giving way to strong, cold winds Saturday.

The North Island will escape this Southern Ocean blast for the most part - while showers and wind are predicted for North Island centres, the high won't tumble much further than they have done this week, says Philip.

Temperatures in Tauranga are expected to be between 17 and 19 degrees this week with showers through until Friday.