El Nino conditions are now present in the tropical Pacific Ocean, with waters in the eastern equatorial Pacific having warmed in recent weeks.

MetService meteorologist Georgina Griffiths says Cyclone Pam produced one of the strongest reversals of the tropical trade winds seen in recent years.

The MetService is forecasting above-average temperatures for April.

'Known as westerly wind bursts, these can kick-start El Nino, since they allow warmer waters to push towards South America,” says Georgina.

Over the last few weeks, waters in the eastern equatorial Pacific, the El Nino breeding ground, have warmed to the point that El Nino thresholds have now been crossed.

The Southern Oscillation Index (SOI), a measure of pressure between Darwin and Tahiti, is also now sitting in El Nino territory (-1.1).

El Nino conditions are forecast to continue through the southern winter (with a 60 per cent chance of continuing El Nino conditions). But what does that mean for New Zealand?

'In the short-term, weather sequences, rather than El Nino, will influence New Zealand's rainfall and temperatures,” adds Georgina.

The MetService outlook for April indicates above-average temperatures right across the country, including the Bay of Plenty. Highs are expected for the start of April, producing generally drier and warmer conditions than usual for the first week of the month.

'But for the remainder of April, lows are forecast to move into the New Zealand region, bringing unsettled, and often wet weather to the country,” says Georgina.

Summary of April predictions:

* Lows to dominate New Zealand's weather for much of April.

* A warmer than average April is expected across New Zealand.

* Above normal April rainfall for the north and west of the South Island, also from Taranaki to Wellington.

* Near normal April rainfall for the north and east of the North Island, the eastern South Island, and Southland.