Aotearoa New Zealand has now gone almost four years without registering a notably cooler-than-average month, with the country also just experiencing its 7th warmest year on record.

Unusually high atmospheric pressure near New Zealand during 2020 helped cause patterns of atmospheric circulation that suppressed rainfall over northern parts of the country. 

According to New Zealand’s National Institute of Water and Atmospheric Research (NIWA), 2020 was the driest year on record for the North Island’s Auckland, Hamilton and Whatawhata. This is an impressive feat at Hamilton, which has rainfall data available back to 1905.

This abnormally dry weather was also frequently accompanied by above-average temperatures throughout the year.

Overall, 2020 was New Zealand’s 7th warmest year on record, with a mean national temperature that was 0.63ºC above the 1981-2010 average. This came in behind the record of 0.84ºC above average in 2016.

Image: New Zealand's annual national temperature anomalies. Source: NIWA

NIWA pointed out that last year’s top-ten temperature ranking is consistent with a long-term trend of rising temperatures in the country. 

Six of the last eight years have all been among the country’s warmest on record. It’s also worth noting that six months during 2020 were more than half a degree warmer than the long-term average, while the remaining six months were all near-average. 

According to NIWA, “it has now been 47 months since New Zealand has had a month with below average temperatures." 

NIWA defines below-average temperatures as being less than -0.50°C of the long-term average. The country’s last below-average monthly temperature was observed in January 2017.