2020’s warnings of extreme weather
A warm, dry year for South Canterbury, including one record-breaking day in winter, has also come with a warning from a leading scientist who says climate change will lead to drier conditions and more extreme weather.
Data included in the National Institute of Water and Atmospheric Research’s (Niwa) annual climate summary, released yesterday, shows Timaru had a mean temperature of 11 degrees Celsius during 2020, compared to a long-term average of 10.6C, Waimate experienced an average of 11.7C (long-term average 10.9C) and Aoraki/ Mt Cook village had an average temperature of 9.5C (long-term average 8.8C).
Niwa climate scientist Ben Noll said 2020 had been a particularly dry year for South Canterbury, with Timaru recording 349 mm of rainfall, well below its long-term average of 550mm.
Waimate recorded 373mm, also well below its long-term normal of 536 mm, and Aoraki/Mt Cook recorded 3696 mm, below its long-term normal of 4285 mm.
‘‘We’ve had abnormally high persistence of higher than normal air pressure patterns, and when you have frequent high pressure patterns that decreases the chance for rainfall,’’ Noll said.
Among the weather extremes for South Canterbury was August 30, when Timaru reached 25.1C, the highest winter temperature for the town since records began in 1885, while on the same day, Waimate also recorded its highest winter temperature (23.4C) since its records began in 1908.
In contrast, on October 16, Timaru recorded -4.5C, the lowest October temperature for the town since records began.
The warm weather in August also meant snow depths were about half of what is usual for the time of year at several Niwa snow and ice monitoring sites, including Mueller Hut at Aoraki/ Mount Cook National Park, which had only 45 per cent of its usual snow depth.
Aoraki/Mt Cook village also recorded a mean minimum temperature for the year of 4.4C, the fourthhighest since records began in 1929, and about 0.8C above the average.
The climate survey makes special mention of the Lake O¯ hau fire in October, which destroyed about 50 homes and killed at least 300 livestock.
Noll said as climate change leads to drier conditions, so too must people become more vigilant of the fire risk.
‘‘We need to be aware of the fact that conditions are going to get drier and lead to more extreme weather events.’’
Meanwhile, the warm weather also led to considerably drier than average soil moisture levels across South Canterbury throughout the year.
Noll said the three month JanuaryMarch outlook pointed to above average temperatures, although cool snaps can be expected from time to time.
‘‘However, rainfall is predicted to be near or above normal, and long dry spells are expected to be interspersed with periodic, sometimes heavy, rain,’’ he said.