Another tropical cyclone could form over the next few days to the north of Aotearoa, forecasters say.
It could be the third of the season, after tropical cyclone Mal barreled past Fiji in November, and tropical cyclone Lola smashed into Vanuatu in October.
NIWA said this year a large patch of Moananui a Kiwa / the Pacific Ocean is warmer than normal.
"NZ has felt the effects of this."
The agency said the warm Pacific waters have caused different effects to atmosphere conditions, versus past El Niño events.
Stephen Glassey, a meteorologist from Te Ratonga Tirorangi / MetService, told the NZ Herald there's a moderate risk of a cyclone forming near the Solomon Islands mid-next week.
It's also possible a low-pressure front hanging northeast of Fiji could move west, into a part of the ocean where it's easier for cyclones to form.
“There’s no indication that we’ll get a tropical cyclone coming toward New Zealand at this stage," Glassey added.
Ben Noll, meteorologist at NIWA, told the NZ Herald we're yet to see what damage the possible cyclone could do here.
“You can start to see that increased risk for a [cyclonic] system forming during the first week to 10 days of the month."
Noll said the wet weather forecast for Te Ika a Māui / North Island in December has nothing to do with tropical cyclones.
Rather, it's El Niño that's boosting sea surface temperatures in the eastern and western Pacific, which could provide the fuel for more cyclones.
NIWA's models have forecast a higher risk of cyclones across the western Pacific.
“As for exactly where or when, it’s still a bit tenuous", Noll added.
“However, given that the first two cyclones of the season swung near us, it’s impossible to say exactly what the third one will do."
Another factor is the Madden-Julian Oscillation (MJO), which NIWA said could contribute to cyclone formation.
For Aotearoa, the risk of cyclones is lower due to a high-pressure system above us over summer, which makes it harder for large storms to push their way in.
The tropical cyclone season lasts from the start of November, until the end of April.
