While much of the country woke up to windy and showery conditions to start the week, it's Wednesday when things will really deteriorate.

Strong southwesterlies over New Zealand are the hangover from a busy weather weekend, but the frontal system which brought significant rain is now moving away from the country.

Looking towards the Mount in a strong Southerly breeze blowing sand along the beach. Photo: Mark Cairns/File photo.

The southwest flow will ease over the next few days, making Tuesday the pick of the week with afternoon fine spells on the cards for all the major centres.

The entire regime will change on Wednesday when a potent cold front races up the country. This front will spearhead a period of gale southerlies affecting eastern regions of both islands and the capital, says MetService meteorologist Angus Hines.

The polar air in behind the southerlies will bring a noticeable drop in temperature, plunging the country back into winter-like conditions after a fairly mild start to spring.

Most of the South Island can expect single digit highs on Thursday, says a statement from the weather organisation. The combination of strong, cold southerlies and frontal precipitation is a recipe for snow to low levels.

Current forecasts are for snow to 300m around Southland, Otago, Canterbury and Marlborough, and 500m about parts of the North Island.

'To top it all off, significant and potentially damaging swells are going to charge up both sides of the country, starting Wednesday evening. This will be most noticeable along the east coast, where such swells are uncommon.” Those waiting for more sunshine will need to wait until the end of the week; a ridge of high pressure extends over the country on Friday.

Strong southerlies on Thursday morning, after the front. Courtesy of MetService Weatherscape.

Due to the polar air which has been dragged over New Zealand earlier in the week, temperatures will remain cool. Overnight lows will be especially chilly, and frosts are likely to develop in sheltered areas across both islands.