Weather records were broken in parts of Northland, including Kaikohe, which recorded New Zealand's wettest location relative to normal in June with nearly 300mm of rain.
According to NIWA's seasonal climate outlook, it was the country's warmest June on record, with every long-term monitoring station observing either above or well above average mean temperatures.
NIWA climate scientist Gregor Macara said for Northland more north easterlies that generally brought warm air from the sub tropics, coupled with higher than normal sea surface temperatures and a gradual rise in temperatures consistent with climate change, contributed to a very warm June.
"Northland's temperatures are pretty consistent with what's observed throughout the country in June. We are an island nation so the climate is characterised as maritime.
"We'll still have variability but ultimately underpinning all that is that the baseline temperatures will continue to rise because of climate change," Macara said.
Rainfall was 149 per cent of normal in eastern parts of Northland in June.
The 298mm of rain that fell in Kaikohe was 196 per cent of normal for that month.
The highest mean air temperature for June of 14.8 degrees C was recorded in Kaitaia, a two degrees C departure from normal since records there began in 1948.
Kerikeri recorded the second highest mean air temperature of 13.8 degrees C since records there began in 1945, Cape Reinga (14.7) and Whangārei (14.1) were the third highest, and Kaikohe at 13.3 degrees C the fourth highest.
In terms of the mean maximum air temperature, Whangārei led the country with a reading of 18.3 degrees C— that's a two degrees C departure from normal since records began in 1967.
Kerikeri recorded the highest mean minimum air temperature of 10.1deg C, Kaitaia (11.9) the second highest, Cape Reinga (12.7) the third highest, and Whangārei (10.6) and Kaikohe (7.5) were the fourth highest.
The 102km/r extreme wind gust was the second highest for Dargaville since records there began in 1997 while Kaikohe recorded the fourth highest at 83km/h.
NIWA's climate summary for July to September predicts above average temperatures, and near average rainfall, soil moisture, and river flows.
Last year, parts of Northland had their warmest and wettest winter on record as a seasonal climate outlook by NIWA showed winter 2020 was New Zealand's warmest winter on record.