Climate Index shows mildest winter in five years

Climate Index shows mildest winter in five years

By October 21, 2020Climate Risk, News

stormThe Australian Climate Index, compiled by Finity's climate risk team, showed winter was relatively benign across most of Australia, with the Index falling to levels not seen since winter 2015.

The Index, measures the occurrence of extreme weather conditions and sea levels and how they change over time compared with a reference period. The reference period is 1981 to 2010.

Through winter, it shows temperatures were more benign than the reference period average. Extreme high temperatures occurred less often, indicative of fewer extremely hot 24 hour day/night periods. However, the extreme low temperature index continued to be positive, indicative of minimum temperatures being warmer than the reference period average. According to the Bureau of Meteorology, the season was the sixth warmest winter on record1.

Only four out of 12 regions experienced extreme rainfall that was above the reference period average.

“The winter of 2020 is a reminder that despite a long-term trend of increasing temperatures and lower rainfall, thankfully not every season will see extreme weather,” said Rade Musulin, Finity.

However, Mr Musulin said Australia may be about to see increased rain and tropical cyclones as we move into summer and 2021. This is the result of the El Nino-Southern Oscillation (ENSO) weather system, which entered a La Niña phase in mid-September. Some past La Niña seasons have seen extreme events, including Cyclone Tracy in 1974 and the Queensland floods in 2010-20113. Another finding from the Index is that extreme wind conditions were also below the reference period average, for every region across Australia through the winter.

Above average rainfall and a 66% chance of more tropical cyclones than average have been forecast by the Bureau of Meteorology.

The Australian Climate Index is updated every quarter. It shows changes in the frequency, or rate of occurrence, of extreme high and low temperatures, heavy precipitation, dry days, strong winds and changes in sea levels across 12 regions that are climatically similar. It is calculated at the end of each season, following the release of data from the Bureau of Meteorology. Each season is compared to the same season in previous years and against a reference period of 1981-2010.

Read more about the Index, which is published by the Actuaries Institute.

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References to temperatures, dryness etc. are based on the data underlying the AACI, which tracks changes in the frequency of extreme high and low temperatures, heavy precipitation, dry days, strong wind and changes in sea level, mainly concentrating on the 99th percentile of observations.