Climate Summary for July 2023

04 August 2023

New Zealand’s 4th-warmest July on record

Temperature	Well above average (>1.20°C above average) or above average (0.51-1.20°C above average) temperatures were observed for most of the country. Pockets of near average temperatures (±0.50°C of average) were observed in isolated parts of North Canterbury, Wellington, Gisborne, and northern Northland.
Rainfall	Above normal (120-149% of normal) or well above normal (>149% of normal) rainfall was observed in eastern and southern parts of the South Island. Rainfall was below normal rainfall (50-79% of normal) or well below normal (<50% of normal) for inland, western, and northern parts of the South Island, and much of the North Island.
Soil Moisture	At the end of the month, soil moisture levels were near normal for most of the country. Above normal soil moisture was observed in eastern parts of Otago, and coastal parts of southern Marlborough. Below normal soil moisture was observed in parts of the Mackenzie Basin.

Overview

July 2023 mean sea level air pressure was lower than normal near and over Aotearoa New Zealand, and higher than normal to the northwest of the country. This was associated with more southwesterly winds than normal. Sea surface temperatures near New Zealand remained higher than average, with marine heatwave conditions persisting in coastal waters near the South Island and lower North Island.

It was a relatively warm July throughout New Zealand, with well above average (>1.20°C above average) or above average (0.51-1.20°C above average) temperatures observed for most areas. Pockets of near average temperatures (±0.50°C of average) were observed in parts of North Canterbury, Wellington, Gisborne, and northern Northland. Overall, the nationwide average temperature in July 2023 was 9.1°C. This was 1.1°C above the 1991-2020 July average, making it New Zealand’s 4th-warmest July since NIWA’s seven station temperature series began in 1909. Globally, July was an exceptionally hot month. The Copernicus Climate Change Service and World Meteorological Organization announced that the first three weeks of July 2023 were the warmest three-week period on record, and that it was “extremely likely” that July 2023 would be the hottest month on record.

July was a wet month for eastern and southern parts of the South Island. Rainfall was above normal (120-149% of normal) or well above normal (>149% of normal) in eastern parts of Canterbury and Otago, and southern parts of Southland. For much of the remainder of the country, it was a relatively dry month. Rainfall was below normal rainfall (50-79% of normal) or well below normal (<50% of normal) for northern Fiordland, inland Otago, much of the West Coast, Nelson, Marlborough and Tasman, western and inland parts of the North Island from Wellington to southern Auckland, southern Hawke’s Bay, Bay of Plenty, and eastern Northland. Rainfall was near normal (80-119% of normal) about the northwestern tip of the North Island, eastern Gisborne, the Tararua District, Wairarapa, and the northern West Coast.

Further highlights:

The highest temperature was 21.1°C, observed at Wairoa on 18 July.
The lowest temperature was -9.1°C, observed at Cass (inland Canterbury) on 7 July.
The highest 1-day rainfall was 199 mm, recorded at Akaroa on 22 July.
The highest wind gust was 180 km/h, observed at Cape Turnagain on 1 and again on 16 July.
Of the six main centres in July 2023, Auckland was the warmest, Christchurch was the coolest and wettest, Hamilton was the driest, Tauranga was the sunniest and Dunedin was the least sunny.
Of the available, regularly reporting sunshine observation sites, the sunniest four regions in 2023 so far are Mackenzie Basin (1433 hours), Taranaki (1403 hours), wider Nelson (1403 hours) and Tasman (1369 hours).