Climate

Wet end to the year for the North Island and north-eastern South Island

2018: New Zealand’s equal-2nd warmest year on record

Very wet for eastern and inland parts of the South Island

Spring 2018: a season of weather swings for New Zealand

Mean summer temperatures are about equally likely to be near or above average. Near normal summer rainfall is likely for most regions; however, the north of the North Island has about equal chances for below normal or near normal rainfall and the west of the South Island has about equal chances for above normal or near normal rainfall.

A dry month for much of New Zealand

The November 2018 – January 2019 atmospheric circulation around New Zealand is forecast to be characterised by higher pressure than normal around the country and lower pressure than normal to the southwest.

Southwest Pacific Tropical Cyclone Outlook: Near-normal tropical cyclone activity overall during November-April, but increased east and reduced west of the Date Line; multiple severe tropical cyclones expected.

A wet start to spring for some but dry for most

The consensus from international models is for the tropical Pacific to transition toward El Niño over the next three-month period (68% chance over October – December 2018). The probability for El Niño conditions being established remains high until autumn 2019, with a 71% chance for El Niño conditions over the April – June 2019 period.

ENSO-neutral conditions continued across the tropical Pacific during July 2018. The Southern Oscillation Index (SOI) was in the neutral range, with a preliminary value of +0.2 for July 2018. Surface ocean waters in the central and eastern equatorial Pacific continued to warm during July but remained in the neutral range. The subsurface ocean remained warmer than average in the eastern equatorial Pacific during July, but anomalies weakened slightly compared to June.

A dry start to winter for much of the South Island.

El Nino – Southern Oscillation (ENSO) neutral conditions continued across the tropical Pacific during June 2018. The Southern Oscillation Index (SOI) was slightly negative at about -0.7 during the past 30 days (on the El Niño side of neutral). The central equatorial Pacific experienced warming sea surface temperatures (SSTs) for the third consecutive month and was slightly above average for the time of year.

A warm start to autumn, then cooler and unsettled at times.