The strengthening climate pattern known as El Nino has continued to intensify in the tropical Pacific Ocean over the last few months.

The system, which occurs as the ocean and the atmosphere reinforce each other, traditionally brings variable levels of wind and rain.

New Zealand has experienced more frequent southerly outbreaks than usual this winter. Photo: File.

'We have a major El Nino in play,” says MetService meteorologist Georgina Griffiths. Warmer than usual seas in the equatorial Pacific Ocean is one of the obvious signs of an El Nino - the so-called ‘warm tongue'.

This pool of unusually warm water upsets the normal balance of trade winds and weather in the tropics.

As a result, the sea temperatures across the eastern half of the Pacific are now in excess of 2C above normal.

'The warmth in the Pacific Ocean has now reached levels not seen since the 1997/98 El Nino,” says Georgina.

'So far this winter, we have already seen solid signs of El Nino in the New Zealand region. During June and July, the country experienced more frequent southerly outbreaks than usual - standard El Nino winter fare for us.”

The southerlies have resulted in below average temperatures overall, for the South Island in June and July and for the North Island since the middle of June.

The seas around our coastline are also colder than usual, particularly off the east coast. El Nino will likely continue into early 2016, and there is every indication that it will remain strong for the rest of this year.

It traditionally peaks towards the end of the calendar year, but it does pay to remember that any effects felt here in New Zealand may not peak at the same time.

'A textbook El Nino spring (September - November) is much colder than usual,” adds Georgina, 'with frequent, stormy, south-westerlies across the country.

'As we head towards Christmas, those winds typically tilt westerly, drying out eastern parts of both Islands.

'New Zealand farmers need to monitor this El Nino.

'While it effects tend to diminish as you move away from the tropics, New Zealand has shown clear impacts from strong El Nino events in the past.

'We also urge farmers to investigate what their typical response is.”