Climate Summary for July 2015

A dry month for many parts of the country.

Overview

Overall, July 2015 was characterised by air pressures which were higher than normal over and to the northwest of the country, while lower pressures than normal were observed to the south of New Zealand. This circulation pattern resulted in slightly more westerly airflows than normal over New Zealand. The westerlies were interrupted by outbreaks of cold southerlies that delivered snowfalls to low elevations, and anticyclones which resulted in spells of frost.  After a particularly eventful June, July was a relatively settled month, although there were still a number of extreme events as expected for this time of year (see Highlights and extreme events section for further details).

It was a dry July for many parts of New Zealand. Specifically, rainfall was below normal (50-79% of the July normal) or well below normal (< 50% of the July normal) in parts of every region except Tasman, Nelson, West Coast and Southland. It was especially dry in eastern parts of South Canterbury, North Otago and Central Otago which received just 20% or less of normal July rainfall. In contrast, rainfall was above normal (120-149% of July normal) for much of West Coast and parts of Auckland. Auckland received a considerable proportion of its monthly rainfall from downpours associated with frontal activity. Soil moisture levels have remained lower than normal in eastern parts of New Zealand. As of 1 August 2015, soils were notably drier than normal for Hawke’s Bay, coastal Wairarapa, and eastern parts of Marlborough, North Canterbury, South Canterbury and Otago. Elsewhere, soil moisture levels were typically near normal for this time of year.

It was a cool month for many parts of the North Island and upper South Island. Mean temperatures were below average (0.51°C to 1.20°C below the July average) in parts of the Far North, Bay of Plenty, Gisborne, Wairarapa, West Coast, and Tasman. Mean temperatures were also below average in coastal South Canterbury and North Otago, mostly due to daily minimum temperatures which were well below average (> 1.20°C below the July average). In contrast, the Mackenzie Country and Banks Peninsula recorded above average temperatures (0.51-1.20°C above the July average), while mean temperatures were well above average (> 1.20°C above the July average) in parts of Central Otago. Temperatures were typically near average (between -0.50°C to +0.50°C of the July average) for the remainder of the country. The nation-wide average temperature in July 2015 was 7.8°C (equal to the 1981-2010 July average from NIWA’s seven station temperature series which begins in 1909)^[1].

It was a sunny month for many parts of New Zealand, with the majority of the country receiving above normal sunshine (110-125% of the July normal). Sunshine hours were well above normal (> 125% of the July normal) in Marlborough, Central Otago and the Southern Lakes. Parts of Taranaki received near normal July sunshine (90-109% of the July normal).

Further Highlights:

• The highest temperature was 21.2°C, observed at Christchurch (Riccarton) on 26 July.
• The lowest temperature was -10.2°C, observed at Hanmer Forest on 12 July.
• The highest 1-day rainfall was 91 mm, recorded at Franz Josef on 14 July.
• The highest wind gust was 152 km/hr, observed at Cape Turnagain on 5 July
• Of the six main centres in July 2015, Auckland was the warmest and wettest, Christchurch was the coolest, Dunedin was the driest and cloudiest and Tauranga was the sunniest.
• Of the available, regularly reporting sunshine observation sites, the sunniest four centres so far in 2015 (1 January to 31 July) are: Blenheim (1555 hours), Whakatane (1539 hours), Appleby (1512 hours) and Waipara West (1489 hours).

Download the full report:

Climate Summary July 2015 [533.58 KB]

Climate statistics for July 2015 [69 KB PDF]

For further information, please contact:

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