New Zealand soil moisture deficit compared with historical average, January 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. Graphic: NIWA

4 March 2013 (NIWA) – February rainfall totalled less than 15 mm (and also less than 15 percent of February normal) in parts of Northland, Auckland, and the Bay of Plenty. It was the driest February on record for Leigh (north Auckland), and Milford Sound. In the case of Leigh, it was also the driest month (of any month) in records which began in 1966. The dryness was widespread. Rainfall was less than 25 percent, or a quarter, of February normal around Taupo, in parts of Gisborne and Hawkes Bay, and along the West Coast of the South Island. Less than half (50 percent) of normal February rainfall was generally observed across the remainder of the country. The exceptions were between Wanganui and Wellington, in Central Otago and the Lakes District (with near normal rainfall); and Marlborough and the Kaikoura coast (with rainfall between 50 and 80 percent of February normal). As at 1 March 2013, extreme soil moisture deficit (more than 130 mm of deficit) was evident in Northland, Auckland, Waikato, the Bay of Plenty region (including Taupo), Gisborne, Hawkes Bay, Wairarapa, between Wanganui and Palmerston North, parts of Marlborough, Canterbury, and Central Otago. Significant soil moisture deficit (more than 110 mm of deficit) was generally observed elsewhere in the North Island, as well as in the Waimea Plains, and across eastern Otago. An adverse event due to drought was declared in Northland on 27 February. Mean temperatures in February were above average (between 0.5°C and 1.2°C above the February average) across the west and south of the South Island, as well as in inland regions of the North Island. In contrast, below average February temperatures (between 0.5°C and 1.2°C below the February average) were observed around the Kaikoura Coast, as well as the east coast of the North Island. Elsewhere, mean temperatures were near average (within 0.5°C of the February average). The nation-wide average temperature in February 2013 was 17.1°C (0.2°C below the 1971-2000 February average), using NIWA’s seven-station temperature series which begins in 1909. Notably, however, in most regions, afternoon temperatures were typically well above February average, and morning temperatures below February average, due to the clear skies and relatively light winds associated with the prevailing high pressures. [more]

Current Climate – February 2013