Niwa climate scientist Gregor Macara said spring (September to November) 2024 was characterised by a higher-than-normal mean sea-level pressure (MSLP) over and surrounding New Zealand, with lower-than-normal MSLP to the southwest of the country.
"This generally resulted in more westerly winds than normal.
"However, a notable exception occurred in October, with more easterly winds than normal over the lower South Island.
"It was a very wet season for Southland and Otago, and rainfall was well above normal for many parts of these regions."
He said several locations in the southern regions received more than double their usual spring rainfall.
Rainfall records were set in Oamaru (335mm), Dunedin Airport (281mm), Dunedin (Musselburgh) (358mm), Lumsden (447mm), Gore (352mm), Invercargill (394mm), Balclutha (343mm) and Tautuku (499mm).
Queenstown (443mm) and Alexandra (176mm) recorded their second-highest spring rainfall totals.
The totals were driven by extremely heavy rainfall events at the start of October and November, which resulted in local states of emergency being declared across the southern region.
One-day spring rainfall records were set during the October 3 flooding event in Green Island, Kaikorai (121mm), Dunedin (Musselburgh) (131mm), Glenledi (174mm) and Inch Clutha (130mm); and during the November 8 flooding event, Franz Josef and Haast recorded their highest one-day spring rainfalls when 373mm and 223mm fell in 24 hours, respectively.
However, at the other end of the scale, Mr Macara said it was a dry November overall for many parts of New Zealand, due to the prevalence of high pressure over the country, and it was especially dry for parts of Central Otago.
Alexandra received just 3mm of rain for the month (8% of normal) and Clyde received 4mm (10% of normal), which made it their second driest month on record.
At the end of November, soil-moisture levels were above normal in southern and western parts of Southland, and eastern parts of Otago.
Elsewhere, near normal soil-moisture levels were typically observed.
Temperatures during spring were above average in eastern parts of Otago, and near average in Southland, inland Otago, the Mackenzie Basin and the West Coast.
No Otago or Southland locations observed record or near-record high or low mean temperatures.
Overall, the nationwide average temperature for spring was 12.9°C, which was 0.8°C above the 1991-2020 spring average, making it New Zealand’s seventh-warmest spring on record.
