A tropical cyclone will likely track northeast of New Zealand in the next couple of days bringing "gusty" winds and rain to some areas, forecasters warn.
Meanwhile, NIWA says a "shot of chilly air" is expected to move over the South Island on Monday night and Tuesday before moving north on Wednesday.
"The centre of Cyclone Gretel is forecast to pass our northeast on Mon & Tue bringing gusty wind to mainly eastern exposed areas," NIWA says. "Expect some beneficial rain mostly north of Auckland."
WeatherWatch says Gretel remains a serious storm but will remain offshore from northern New Zealand.
"The storm is powerful and will not be falling apart before NZ very much, instead, high pressure in the Tasman Sea will guide it further east of Northland, significantly reducing the chances of severe weather here."
But that high-pressure system would reduce the chances of beneficial rain for drought-stricken areas.
"Eastern Northland has some rain chances – and with still over 24 hours to go the computer models may pull the storm a little closer to NZ which could see some rainfall totals lift," WeatherWatch says.
"Winds will climb well over gale around Great Barrier Island, where power cuts may be possible on Tuesday."