A low pressure system east of the North Island is bringing wet weather and cool southerly winds this week.

While rainfall amounts are not expected to be severe, MetService is keeping a close eye on it.

The majority of the rain is forecast to fall north of Napier, with Wednesday looking like the wettest day before southerlies ease during Thursday, says a statement from the weather organisation.

A weakening cold front ushers in showers and overcast skies to places east of the Southern Alps today, as well as a drop in temperatures there for the rest of the week.

Temperatures in Canterbury following this front aren't forecast to exceed 15°C until Friday or Saturday.

Regions to the west of the country's main spine of mountains running from East Cape down to Fiordland will be the sunniest this week, but windy southeasterlies across the lower North Island will make conditions feel cooler.

"Looking ahead to the end of the week, we're monitoring a weather system that's expected to approach the top of the country," says MetService meteorologist Dan Corrigan.

"This could mean a burst of heavy rain for Northland, but there's still a high degree of uncertainty around how the system will move and evolve in the meantime."

A look at rainfall accumulations across the country so far this year shows that central areas have been wetter than usual, but both the north and the south are running dry.

"Showers on Tuesday in Southland, while welcome in such a dry area, are only expected to contribute a small sprinkling of rain.

"On the other hand, eastern North Island regions are already wetter than usual this year."