A cold blast of air from the south has bought sub-zero temperatures to the South Island as storms sweep New Zealand.
And forecasters warn the chill is set to continue as waves of cold air hit New Zealand over the rest of the week.
"A surge of stormy autumn weather is about to engulf the country for a week," Weather Watch says.
"The South Island will be most impacted by the rough weather with several storms, or lows, in the Southern Ocean tracking by this week while high pressure remains just out of reach to the north."
NIWA warns effective temperatures on Monday will fall below sub-zero for most of the South Island due to brisk winds and cold air.
"Have a look at the expected weather conditions for 8am Monday as we go back to work and school," it says.
"So heads up farmers, parents and care takers...dress warmly or get the stock in cover!"
"We will see continued waves of cold air coming at New Zealand as the week unfolds with the South Island getting the brunt of the cold and wind."
And the North Island won't escape either.
"Expect some rain for the upper North Island on Monday morning then easing to showers in the afternoon as westerlies tend a little more southwest for a time," Weather Watch says.
"Early morning rain for the lower western North Island eases to showers, winds gusty from the west then easing from afternoon."
The South Island has already been lashed over the weekend, with gusts well over 120km/hr, and heavy rain for the West Coast.
By 10pm on Sunday MetService had recorded nearly 3500 lightning strikes in one day. Two Air New Zealand flights were forced to divert to Christchurch after being hit by lightning.