Climate summary for January 2017

A tempestuous month, cool for many and very dry in the eastern North Island.

NZ Climate Summary inforgraphic for Jan 2017 [NIWA]

Overview

January 2017 was characterised by significantly lower mean sea level pressure than normal over and to the south of New Zealand. This atmospheric pressure setup caused more southwesterly winds than normal across the country, which encouraged the passage of storms and low temperatures for much of New Zealand throughout the month.

The prevalence of southwesterly winds across the country during January meant that lower than average temperatures for the time of year were experienced in many places. This was especially notable in the west and south of the South Island (including West Coast, Canterbury, Otago, Southland and parts of Tasman) and the west and centre of the North Island (including Waikato and Taranaki), where well below average temperatures (< -1.20°C of the January average) were observed. Below average temperatures (-1.20°C to -0.51°C of the January average) were experienced in many regions, including western Northland, Waikato, inland Bay of Plenty, Taranaki, Manawatu-Whanganui, Wellington, and parts of the South Island regions that experienced well below average temperatures also. In contrast, areas that were sheltered from the prevailing southwest winds, such as eastern Northland, coastal Bay of Plenty, Hawke’s Bay, Gisborne, Marlborough and coastal northern Canterbury, experienced near average temperatures (-0.50°C to +0.50°C of the January average) and a small number of locations in the Hawke’s Bay experienced above average (+0.5°C to +1.20°C of the January average) or well above average temperatures (> +1.20°C of the January average). The nationwide average temperature in January 2017 was 16.4°C (0.7°C below the 1981-2010 January average from NIWA’s seven station temperature series which begins in 1909 [N.B. this is rounded to 1 decimal place]). This was the coldest January since 2014.

The dominant southwesterlies also influenced rainfall patterns across New Zealand in January. Some intense storms delivered heavy rain to the South Island and lower North Island. Much of the South Island, particularly along the West Coast, and in middle and south-coastal Canterbury, Otago and inland Southland, recorded above normal (120-149% of the January normal) or well above normal (>149% of the January normal) rainfall. Parts of the south and west North Island also recorded above normal or well above normal rainfall, particularly in Wellington and Manawatu-Whanganui. In stark contrast was the east of the North Island, where record low rainfall was experienced. It was the driest January on record for Gisborne in over 110 years; just 2 mm of rain (3% of the January normal) fell – records began there in 1905. Well below normal (< 50% of the January normal) or below normal rainfall (50-79% of the January normal) was recorded at numerous sites across the eastern half of the North Island from Northland through to the southern Hawke’s Bay, with only the occasional site in this part of the country receiving near normal (80-119% of January normal) rainfall.

The pattern of sunshine across the country generally followed the pattern of rainfall. Western areas of the South Island and southwestern North Island generally recorded below normal sunshine hours (75-89% of January normal), with a couple of sites recording well below normal sunshine (<75% of the January normal). Wellington, Palmerston North and Paraparaumu recorded their least sunny January on record. In contrast, the Far North recorded above normal sunshine (110-125% of the January normal). Most sites recorded near normal sunshine for January (90-109% of the January normal).

The significant soil moisture deficits in the north and east of the North Island at the end of 2016 continued to worsen in January. Due to limited rainfall for eastern parts of the North Island during January, soil moisture deficits remained much lower than normal for the time of year. As of 1 February, soil moisture levels were much lower than normal across most of the North Island, particularly in Northland, eastern Waikato, Coromandel, inland Bay of Plenty, East Cape, and Hawke’s Bay. Soils were also drier than normal for coastal northern Canterbury. Soils were wetter than normal for the time of year for Tasman, West Coast, Otago and Southland, and near normal soil moisture levels were observed elsewhere.

Further highlights:

• The highest temperature was 33.6°C, observed at Hastings on 12 January.
• The lowest temperature was -1.7°C, observed at Mt Cook Airport on 5 January.
• The highest 1-day rainfall was 309 mm, recorded at Milford Sound on 31 January.
• The highest wind gust was 170 km/hr, observed at Cape Turnagain on 16 January.
• Of the six main centres in January 2017, Dunedin was the wettest, coldest, and least sunny, Auckland and Tauranga were the driest, and Tauranga was the warmest and sunniest.
• Of the available, regularly reporting sunshine observation sites, the sunniest four locations in 2017 (1 January – 31 January) were Gisborne (315 hours), Whakatane (301 hours), Napier (298 hours) and Kaitaia (286 hours).

Download 

January 2017 Monthly Climate Summary [568KB PDF]

Climate Statistics for January 2017 [74KB PDF]

Contact

For further information, please contact:

Mr Chris Brandolino - Principal Scientist – Forecasting,
NIWA National Climate Centre, Tel. 09 375 6335