Warmest recorded November closes 12th warmest Spring
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Temperature |
Temperatures were near average (-0.50°C to +0.50°C of the spring average) for most of New Zealand, while areas in the eastern North Island and parts of Canterbury observed above average temperatures (+0.51°C to +1.20°C of the spring average). A small portion of coastal southern Canterbury recorded below average temperatures (-1.0°C to -0.5°C of the spring average). |
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Rainfall |
Rainfall was near normal (80-119% of the spring normal) for the majority of the country. Areas of below normal rainfall (50-79% of the spring normal) were observed in parts of Bay of Plenty, Manawatu-Wanganui, Gisborne, Hawke’s Bay, Wellington, coastal north Canterbury and interior south Canterbury. Areas of above normal rainfall (120-149% of the spring normal) were observed in parts of the Coromandel Peninsula, southern Hawke’s Bay, Westland, central Canterbury, along with eastern Otago and Fiordland. |
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Soil moisture |
At the end of spring 2019, soil moisture levels were below normal for much of the upper and eastern North Island, along with scattered portions of Tasman, Marlborough and Canterbury. Above normal soil moisture levels were observed in the lower west coast of the North Island, interior Gisborne, Banks Peninsula and in parts of Otago and Southland. |
Overview
Spring 2019 was characterised by lower than normal mean sea level pressure over, south and east of New Zealand. This pressure setup resulted in a southwest airflow anomaly across the country (i.e. more southwesterly winds than normal).
Variable temperatures started the spring season in September with warm subtropical winds mixed with chilly southerlies. The cool temperatures were influenced by a sudden stratospheric warming (SSW) event, which occurred in the polar stratosphere during late August and peaked in mid-September. Temperatures as a whole were near average for the time of year in September and continued on the near average note in October, before prevailing northwesterlies in November brought unseasonably warm temperatures and New Zealand’s warmest November on record. In terms of rainfall, it was variable throughout the season as well, with rainfall below normal in the southern portion of both islands during September. Rainfall varied considerably based on geographic location in October, with eastern areas generally experiencing wetter conditions while western areas tended drier. Rainfall patterns were contrasting during November, owing to a northwesterly air flow anomaly. Below to well below normal rainfall occurred in the North Island during the month, while the western South Island experienced above or well above normal rainfall, leading to a marked increase in hydro lake storage levels.
The main climate influencers during spring 2019 were the SSW event in September and a strongly positive Indian Ocean Dipole (IOD) event in October and November. The IOD’s hallmark is cooler than average sea surface temperatures in the eastern Indian Ocean near Indonesia and warmer than average sea surface temperatures in the Arabian Sea. This particular IOD event was of near-record strength and caused abnormally dry conditions across Indonesia and Australia over the past several months. For New Zealand, it brought more westerly quarter winds than normal during spring, from cooler, drier southwesterlies in October to warm, moist northwesterlies in November.
For the season as a whole, spring had near average temperatures across the country. The nationwide average temperature for spring 2019 was 12.5°C (0.4°C warmer than the 1981-2010 spring average, using NIWA’s seven-station temperature series which begins in 1909). This makes the spring 2019 the 12th-warmest spring on record.
Further Highlights:
- The highest temperature was 34.6°C, observed at Kawerau on 3rd November, which is also New Zealand’s third-highest spring temperature on record.
- The lowest temperature was -8.0°C, observed at Middlemarch on 10 September.
- The highest 1-day rainfall was 226 mm, recorded at Rings Beach in the Coromandel Peninsula on 9 September.
- The highest wind gust was 191 km/hr, observed at South West Cape on 22 November.
- Of the six main centres, Auckland and Tauranga were the warmest, Dunedin was the coolest, Wellington was the wettest, Christchurch was the driest, Tauranga was the sunniest while Hamilton was the least sunny.
- Of the available, regularly reporting sunshine observation sites, the sunniest four regions in 2019 so far are Wider Nelson (2582 hours), Marlborough (2527 hours), Hawke’s Bay (2466 hours), and Bay of Plenty (2412 hours).
