A soggy and exceptionally warm November
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Rainfall |
Rainfall was above normal (120-149% of normal) or well above normal (>149% of normal) for the majority of the North Island and South Island. Near normal rainfall (80-119% of normal) was observed in patches about Cape Egmont, the Māhia Peninsula, south of Cape Kidnappers, eastern Wellington, the northern Canterbury Bight, parts of coastal Southland and parts of Otago. Rainfall was below normal (50-79% of normal) or well below normal (<50% of normal) in Fiordland and eastern Otago. |
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Temperature |
It was the warmest November on record for Aotearoa New Zealand. Temperatures were above average (0.51°C to 1.20°C above average) or well above average (>1.20° above average) for the majority of Aotearoa New Zealand. |
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Soil Moisture |
At the end of November, soil moisture levels were well above normal for much of the North Island, as well as parts of Marlborough, Tasman, Canterbury and Southland. Small patches of below normal soil moisture levels were observed in eastern Wellington, near Dunedin and parts of Rakiura/Stewart Island. Elsewhere, near normal soil moisture levels were observed. |
Overview
November 2022 was characterised by lower-than-normal mean sea level pressure (MSLP) over Aotearoa New Zealand, with a strong area of higher-than-normal MSLP to the east. This pressure setup resulted in northerly air flows being more common than normal, drawing warm and moist air from the sub-tropics and tropics across the country. Sea surface temperatures near New Zealand were also exceptionally warm; 1.1-1.7˚C above average. These factors, combined with an active sub-tropical jet stream, led to an increase in the frequency and intensity of low pressure systems, heavy rainfall events and thunderstorm outbreaks.
The observed MSLP patterns for the month were associated with a continuation of a moderate La Niña event and a positive Southern Annular Mode (SAM). The SAM is a proxy for the location of a belt of westerly winds that encircle the Southern Ocean and occasionally protrude into the mid-latitudes. Additionally, in the Indian Ocean, a see-saw of anomalous sea surface temperatures called the Indian Ocean Diploe (IOD) began to wane, but still had an impact on New Zealand’s weather.
These weather patterns led to a wet month with several landfalling atmospheric rivers and bouts of thunderstorms, causing widespread saturated soils across the North Island and parts of the South Island. Rainfall was above normal (120-149% of normal) or well above normal (>149% of normal) nearly everywhere, but there were areas of near normal rainfall (80-119% of normal) observed in patches about Cape Egmont, the Māhia Peninsula, south of Cape Kidnappers, eastern Wellington, the northern Canterbury Bight, parts of coastal Southland, and parts of Otago. Meanwhile, rainfall was below normal (50-79% of normal) or well below normal (<50% of normal) in Fiordland and eastern Otago.
November 2022 was +1.8˚C above the 1981-2010 average from NIWA’s seven station temperature series, making November 2022 the warmest November on record, surpassing the record set just last year. The top three warmest Novembers on record have all occurred since 2019.
Note that due to data collection issues, there are less stations than normal in this summary. This does not affect the results of the seven station series.
Further Highlights:
- The highest November temperature was 30.2°C, observed at Hanmer Forest on 15 November.
- The lowest November temperature was -1.8°C, observed at Waipara North on 11 November.
- The highest 1-day rainfall was 146 mm, recorded at Mt Cook Airport on 2 November.
- The highest wind gust was 167 km/h, observed at South West Cape on 2 November.
- Of the six main centres in November 2022, Auckland was the warmest, Dunedin was the coolest and driest, Hamilton was the wettest and least sunny, and Wellington was the sunniest.
- Of the available, regularly reporting sunshine observation sites, the sunniest four regions in 2022 so far are Taranaki (2388 hours), Bay of Plenty (2335 hours), Wider Nelson (2325 hours), and the interior of Canterbury (2251 hours).
