Warmest November on record see Northland temperatures soar

Northland centres had some of the warmest November temperatures on record last month as the sun shone on much of the region.

Last month was New Zealand's warmest November on record and a number of Northland centres recorded their hottest temperatures for the month since records began.

But while parts of Northland were warmer than normal, others had more rainfall than usual for the month.

The Niwa climate summary for the month said this November was characterised by higher than normal mean sea level pressure (MSLP) located to the southeast of Aotearoa New Zealand, with lower than normal MSLP over eastern Australia.

This set up resulted in a northeast airflow anomaly - more northeasterly winds than normal. These warm and humid northeasterly winds from the subtropics combined with well above average sea surface temperatures surrounding the country, resulting in New Zealand's warmest November on record.

Overall, the nationwide average temperature in November was 15.4°C. This was 1.7°C above the 1981-2010 November average, making it New Zealand's warmest November since Niwa's seven station temperature series began in 1909.

November 2021 surpassed November 2019 as the warmest on record, and three of the four warmest Novembers have now occurred since 2013, Niwa meteorologist Seth Carrier said.

In Northland, Whangārei, Kerikeri and Kaikohe all recorded their highest mean air temperatures for the month since records began.

Whangārei recorded a mean air temperature for the month of 18.7C-2.2C above normal since records began in 1967.

Kerikeri recorded a mean air temperatures of 17.9C, 2.1C above normal since records began in 1945 and Kaikohe recorded 17.2C, 2.2C above normal since 1973.

Kaitaia and Cape Reinga recorded their second highest mean since records began there in 1948 and 1951 respectively of 17.9C (2C above normal) and 17.3C, (1.7C).

Whangārei and Kaikohe both recorded their second highest mean maximum air temperatures for the month. Whangārei was at 23C, 2.4C above normal and Kaikohe 21.2C, 2.4C above normal.

On November 21, Dargaville recorded its second highest daily temperature for the month since records began there in 1943 with 26.2C.

While temperature records were set across much of Northland, parts of eastern Northland had up to 50 per cent more rain than normal for the month.

Northland is in for a warmer than normal summer period, but with a La Nina weather pattern there's also the risk of cyclones hitting the region.

Niwa's climate summary for December to January is predicting that Northland has a 65 per cent chance of having above-average temperatures, with rainfall likely to be near or below average.

However, Niwa meteorologist/forecaster Ben Noll said as a result of La Nina, the risk of Pacific tropical cyclones hitting the region was elevated.

"Those with marine interests north of the country should closely monitor the situation. On average, one tropical cyclone passes near the country each year, bringing heavy rain, strong winds, and rough seas," he said.

In Northland temperatures are very likely to be above average (65 per cent chance). Rainfall totals are most likely to be near normal (45 per cent chance).

"The potential for sub-tropical low pressure systems is elevated, particularly in the northern part of the region such as Northland. These systems can bring heavy rainfall and cause flooding," Noll said.