North Island voters can expect to be lashed by rain and wind but there will be finer weather further south, the MetService says.
Meteorologist David Miller said a trough meant wet conditions.
Auckland could expect some heavy morning rain, with a possibility of thunderstorms, he said.
The weather would be much the same in Hamilton and Tauranga, with heavy rain and some thunderstorms possible, as well as strong winds.
A severe weather watch was in place for Wellington. "It probably will be ... gusting at about 100 km/h but this is Wellington, so it is nothing too dramatic or unheard of."
