Extreme temperatures across the country are happening far more often than expected.
New research from NIWA has shown that extreme events, such as record-breaking heat waves, have occurred four to five times more frequently in the last decade.
Even with climate change and warming trends considered, New Zealand is still hitting two to three times more extreme high temperatures.
Seventy years' worth of weather data from across the country has been analysed for the study.
It found that extreme weather events are increasing at a faster rate than the average temperature.
New Zealand's east coast is getting less rainfall than normal, experiencing dry conditions twice as often.
NIWA climate scientist and lead author of the study Raghab Srinivasan said the study's data backs up anecdotal evidence from the past few years.
"We can say much more confidently that climate change is no longer a thing of the future. It is happening to us now," Srinivasan said.
"The extreme events that we were once warned about are playing out across the globe, with droughts, storms and forest fires happening a lot more often than even just a couple of decades ago."
According to the record of global land and ocean temperatures spanning 1880-2020, the seven warmest years have all occurred since 2014, while the 10 warmest years have occurred since 2005.
"We instinctively know that we're experiencing more hot, dry days and record-breaking weather events, especially as they're often reported in the news," Srinivasan said.
"This study has given context to this by showing the frequency of these extremes and how they have changed over the last seven decades in New Zealand."
NIWA publishes monthly climate summaries which report on the occurrence of extreme climate and weather events.