A southwesterly is expected to flow over the country this week, bringing showery conditions to much of the North Island.
The good news is that an anticyclone will arrive on Friday and push the rain away.
MetService forecaster Gerard Bellan said there is a risk of thunderstorm activity from Raglan to Manawatu as the front goes through.
"We had quite big swells come up on Sunday, with swell warnings for parts of the coast, including Wellington and Wairarapa. It looks like we get another burst of big swells coming up from southern and eastern parts of the country on Wednesday in the South Island.
"Temperatures are average or slightly below at the moment. We are back into this idea that there will be frosts in some sheltered places as we get clearances overnight, especially in the South Island as we go through the week.
On Sunday night, those based between Queenstown and Wanaka might have noticed a dusting of snow across the Crown Range. A cold front moving up the South Island can be expected to reach the North on Monday.
"Sheltered parts of the North Island can expect frosts later in the week, although a high should spread over and clear things up. Saturday is looking mostly fine at this stage."
Christchurch locals woke to frosty temperatures on Sunday morning: MetService's airport station recorded -0.8C.
In the North Island, Masterton locals were feeling the cold too at 2C.