Extreme heat in New Zealand: a synthesis

Extreme heatwaves are among the fastest-changing meteorological hazards in a warming world. While likely also true for New Zealand, significant knowledge gaps exist relating to the current and future risks associated with extreme heat. Using high-quality station observations dating back to at least 1972, this study presents the first detailed synthesis of the severity, frequency, and persistence of extreme heat experienced by local communities in New Zealand. Results show the hottest days of the year have warmed by more than 0.5 °C over the last 20 years for many populated regions, a rate which exceeds average annual changes across the country. When evaluating the risks associated with unusually extreme events, complex regional differences emerge. While the East Coast of both islands witness higher absolute temperatures during local heatwaves, lower levels of day-to-day temperature variability in the northern half of the North Island will translate to larger risks with further warming over the twenty-first century.