January monthly outlook

January 5, 2017

A cold start to the year

December 2016
December saw regular transitions for the country from high pressure systems to troughs from the west. Aside from the west coast of the South Island and the Canterbury Plains (which were wetter than normal) most places saw normal to lower than normal rainfall. The north and east of the North Island along with Otago had an especially dry month.

After a generally warm start to December, temperatures dropped below average for the second half. December the 29th saw an especially cool night across the country, with Taupo reaching as low as 3 degrees. Overall the month’s average temperature ended up on the slightly cooler side for the west of both Islands, but generally average elsewhere. An especially blustery southerly change moved up the east of the country on December the 12th, bringing with it a sharp drop in temperatures and over 1200 lightning strikes between Otago and East Cape.

The Ocean

Sea temperatures around our coastline remain fairly variable. Waters are currently warmer than usual along the southern and eastern coast of the South Island and along the coast of Northland, but cooler than average elsewhere.

La Nina conditions were very short lived and the event has been eased back to neutral. Most climate models forecast neutral conditions through the rest of Summer. However, the seas are still warmer than average in the South Pacific which could lead to a more active Tropical Cyclone season.

The January Outlook

A southwest flow over the country this week has brought an especially cold start to the month. Next week the pattern changes and highs are likely to favour the North Island. This means a drier than normal month is expected in the north and east of the Island, with normal rainfall expected elsewhere and temperatures returning to around average.  Meanwhile westerlies look to dominate the South Island, with several fronts moving over resulting in higher than normal rainfall in the west and normal rainfall in the east. Temperatures should rise somewhat after the first week, but continue to lie on the slightly cooler side for the west and south.

This month will be one to watch with a low risk of Ex-Tropical Cyclones tracking south over New Zealand. If this were to happen it would result in a wetter and warmer month overall for the North Island.

Bottom line:
Dry for the north and east of the North Island, but wet for the west of the South Island, and about normal elsewhere. After an especially cool start to the year expect a return to average temperatures for most, but remaining on the cooler side for the south and west of the South Island.



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