A sharp cold front is currently located over the South Island and is moving northwards, bringing a colder south to south west change behind it which will go nationwide on Wednesday.
This front is producing persistent heavy rain on the West Coast and significant snow accumulation over the Southern Alps. Frequent lightning is also being observed.
The area of heavy rain around the from will move up to reach about Westport by evening, then sweeps across the North Island overnight and during Wednesday morning. The peak of rain will be around midnight in Wellington and then early morning around Auckland. Isolated thunderstorms and gusty winds are expected with the front.
Elsewhere on Tuesday isolated thunderstorms may affect Northland and Auckland too with more plenty of downpours in the area too (along with sunny spells).
Nor’West gales are possible ahead of the front, mainly through the interior of the South Island near the mountains. Behind the front winds swing Sou’West for many which may rise to gale force around Southland and Otago across Wednesday.
With snow on the mountains and surges of colder Southern Ocean air on both Wednesday and again this Friday/Weekend temperatures will be down for many, especially the lower half of the South Island which have a number of single digit daytime highs in the days ahead. Sub-zero temperatures are expected overnight tonight and even more so for some more sheltered areas on Wednesday night. Even Christchurch has an overnight low of 0 tomorrow night while Alexandra has -3 next few nights.
Eastern areas will have some downpours, rain and even some hail – but overall eastern areas of both islands will be drier than average while the western side of the country will be wetter than average over the next 7 days.
– WeatherWatch.co.nz, an official IBM/TWC business partner