Climate Summary for December 2014

 Soil moisture quite low for most of the country.

Rainfall	Rainfall was below normal (50-79%) or well below normal (< 50%) for many areas of the South Island along and east of the Divide while the far northern part of the island received near normal (80-119%) or above normal rainfall (120-149%). Rainfall for the North Island was greatest for the eastern and northern sections where above normal to well above normal (>149%) rainfall occurred. Meanwhile, the general theme for central and western portions of the island was near normal or below normal rainfall.
Soil Moisture	As of 1 January 2015, soil moisture levels were below normal for the time of year for extensive areas of New Zealand, but especially for the Waikato, lower Hawke’s Bay, Wairarapa and along and east of the Divide in the South Island. Wetter than normal soils for this time of year were evident over parts of upper West Coast for the South Island as well as for northern Gisborne, coastal Bay of Plenty, much of the Coromandel Peninsula as well as central and eastern Northland.
Temperature	December temperatures were above (+0.51°C to 1.20°C) or well above average (>1.20°C above average) for much of the South Island, particularly for areas along and west of the Divide, with mostly near average temperatures (-0.50°C to +0.50°C) east of the Divide. For the North Island, December temperatures were largely near average for most of the island. However, parts of the central and eastern regions recorded below average temperatures (-1.20°C to -0.51°C) with pockets of well below average temperatures (< 1.20°C below average) experienced. A few locations in the Northland, Auckland and Waikato regions observed above average temperatures.
Sunshine	December sunshine was abundant for much of the South Island, especially along and west of the Divide as well as much of Southland and Otago where monthly sunshine hours were above normal (110-125%) to well above normal (>125%). For the North Island, near normal sunshine (91%-109%) was recorded for December.

December 2014 was characterised by higher than normal pressure centred near the Chatham Islands and extending over New Zealand with lower than normal pressures over the Tasman Sea and eastern Australia.  This pressure pattern resulted in an anomalous northeasterly airflow over the country. In terms of temperature, the month of December was a month with two halves, with below average or well-below average temperatures dominating most of New Zealand through the first half of the month. Thereafter, however, the remainder of the month featured much warmer temperatures which compensated for the unusually cool start. In fact, in some cases, the warmth was enough to not only make up for the temperature deficit, but allow for a surplus as monthly mean temperatures went from below average through mid-December to above by month’s end. Examples of this remarkable turnaround are listed below. The nation-wide average temperature in December 2014 was 16.1°C (0.5°C above the 1971-2000 December average from NIWA’s seven station temperature series which begins in 1909)^[1].

The month of December was separated by two distinct temperature regimes:

Location	Mean air temp. to 16 Dec, inclusive (oC)	Departure from normal as of 16 Dec (oC)	Mean monthly air to 31 Dec temp. (oC)	Departure from normal to 31 Dec (oC)
Dargaville	17.1	-0.6	18.4	+0.7
Auckland (Albany)	17.3	-1.1	18.4	0.0
Martinborough	13.5	-3.0	16.1	-0.3
Napier	16.0	-1.7	17.8	+0.1
Wanganui	16.0	-0.9	17.8	+0.9
Wellington (Kelburn)	13.7	-1.8	15.5	+0.1
Hokitika	13.7	-0.7	15.6	+1.2
Blenheim	14.8	-2.0	17.3	+0.6
Hanmer Forest	11.3	-3.2	14.2	-0.2
Christchurch (Riccarton)	14.1	-2.0	16.2	+0.1
Timaru	12.5	-2.0	14.9	+0.5
Ranfurly	13.0	-0.5	15.3	+1.9
Dunedin (Musselburgh)	11.9	-2.0	14.0	+0.2
Queenstown	13.6	-0.6	15.3	+1.2
Gore	12.3	-0.9	14.7	+1.6

The northeasterly wind flow anomaly for the month as a whole contributed to rainfall totals that were above normal (120-149%) or well above normal (> 149%) for central and eastern Northland, Coromandel Peninsula, Coastal Bay of Plenty, Gisborne and Hawke’s Bay regions. The drying orographic effect of air moving westward over elevated land meant that rainfall was below normal (50-79%) for much of the Waikato and parts of the Manawatu-Wanganui regions for the month. However, coastal regions from Taranaki to Wellington received above normal to well above normal December rainfall. Generally speaking for the South Island, with the exception of the northern third of the island, December rainfall was below normal or well below normal rainfall (<50%).

As of 1 January 2015, soil moisture levels were drier or much drier than normal for this time of year for the majority of the country. The driest soils for this time of year are in areas of the Waikato, Wairarapa, and for much of eastern Canterbury and northern Otago regions. Compared to about one month earlier, South Island soil moisture has increased significantly for the Tasman, Nelson and Marlborough regions, but drier than normal soils for this time of year have expanded and even intensified east of the Divide. Soil moisture levels for this time of year have increased or improved, when compared to 1 December 2014, for Gisborne, coastal Bay of Plenty, Coromandel Peninsula as well as central and eastern sections of Northland.  Conversely, soil moisture levels for this time of year have remained low and even deteriorated since early December over the Wairarapa and northern Taranaki, along with much the Waikato region.

December sunshine was abundant for much of the South Island, in particular, along either side of the of the Divide as well as much of Southland and Otago where monthly sunshine hours were above normal (110-125%) to well above normal (>125%). For the North Island, near normal sunshine (91%-109%) was recorded, although below normal December sunshine was evident from the Kapiti Coast to Wellington as well as parts of the Waikato. 

Further Highlights:

• The highest temperature was 32.8°C, observed at Middlemarch on 24 December
• The lowest temperature was -2.4°C, observed at Pukaki on 1 December
• The highest 1-day rainfall was 145 mm, recorded at Hicks Bay on 17 December
• The highest wind gust was 178 km/hr, observed at Cape Turnagain on 7 December
  • Of the six main centres in December 2014, Auckland was the warmest, Dunedin was the coolest and sunniest, Tauranga was the wettest, Christchurch was the driest and Hamilton was the cloudiest
  • Of the available, regularly reporting sunshine observation sites, the sunniest four centres[2] in 2014 (1 January to 31 December) are: Whakatane (2710 hours), Blenheim (2509 hours), Lake Tekapo (2505 hours) and Nelson (2486 hours).

Download the full report:

December Climate Summary (647.32 KB)

Climate statistics table:

Climate statistics for December 2014 [62Kb PDF]

For further information, please contact:

Mr Chris Brandolino NIWA Forecaster – NIWA National Climate Centre Tel. 09 375 6335, Mobile (027) 886 0014