Current Climate - March 2013

March 2013 was dominated by anticyclones ('highs') which were slow moving over and to the east of New Zealand. These highs generally kept rain-bearing weather systems such as lows and fronts away, resulting in a dry, sunny, and warm March for many regions. The remains of ex-tropical cyclone Sandra and an active cold front interrupted this pattern, causing very heavy rainfall on the 18th in the lower North Island. 

Rainfall

March rainfall was around 20 percent of normal in parts of Northland, Bay of Plenty, and Hawkes Bay.  Rainfall was less than 60 percent of March normal for much of the remainder of the North Island north of Stratford, the West Coast of the South Island, parts of Canterbury, Otago, and Southland. It was the driest March on record for Whakatane, Motu, Ohakune, Tiwai Point, and Balclutha. In contrast, the lower North Island and the upper South Island were much wetter than normal for March, with the Kapiti Coast receiving 170 percent of normal March rainfall (over one-and-a-half times normal rainfall), and Kaikoura recording 200 percent of normal rainfall for March (double March normal rainfall).

As at 1 April, extreme soil moisture deficits (more than 130 mm of deficit) evident in parts of: Northland, Auckland, Waikato, Bay of Plenty, Gisborne, and Hawkes Bay, Marlborough and Canterbury.  Significant soil moisture deficit (more than 110 mm of deficit) was observed elsewhere across the North Island north of Palmerston North, as well as across Otago and Southland. Following the declaration of an adverse event due to drought in Northland on 27 February, South Auckland, Waikato, Bay of Plenty, and Hawkes Bay regions were declared in drought on 6 March. A declaration of drought across the entire North Island followed on 15 March, and on 22 March drought was declared in Buller and Grey districts.

Temperature

Mean temperatures for March were well above average (more than 1.2°C above the March average) across northern and central areas of the North Island, and southern and western parts of the South Island. It was the warmest March on record for Leigh, Gisborne, Milford Sound, Manapouri, Wanaka, and Cromwell. Mean temperatures were generally above average (between 0.5°C and 1.2°C above the March average) for all other regions.  The nation-wide average temperature in March 2013 was 16.7°C (0.9°C above the 1971-2010 March average, using NIWA’s seven-station temperature series which begins in 1909).

Sunshine

The dominance of high pressures during March resulted in an extremely sunny month across the North Island and the west of the South Island. Sunshine totals were well above normal (exceeding 125 percent of March normal) across most of the North Island south of Auckland, as well as west of the Southern Alps. Sunshine totals were above normal (between 110 and 125 percent of March normal) for Auckland, Marlborough, Otago, and Southland. Elsewhere, sunshine was close to normal for March. It was the sunniest March on record for Te Kuiti, Taumarunui, Turangi, New Plymouth, Martinborough, and Stratford. Of the available, regularly reporting sunshine observation sites, the sunniest four centres so far in 2013 (January to March) are New Plymouth (928 hours), Whakatane (885 hours), Paraparaumu (855 hours), and Lake Tekapo (830 hours).

Percentage of normal rainfall for March 2013.
End of month water balance in the pasture root zone for an average soil type where the available water capacity is taken to be 150 mm.
Departure from average air temperature for March 2013.