Australia continues to get some respite from last year’s high temperatures, but autumn weather brought extreme rain and rising sea levels.

The Australian Actuaries Climate Index for March-May indicates more extreme weather than in the reference period from 1981-2010, though the high temperature index was below the reference period average for Australia for the second consecutive season after eight years of positive index values.

Only two of the 12 regional clusters which make up the index experienced above reference extreme high temperature values while the extreme low temperature index showed negative values for only the third time since 2012 as minimum temperatures, which were higher than reference period averages for some time, were cooler than those observed between 1981-2010.

This was particularly pronounced in the Central Slopes, which covers inland parts of NSW and QLD and recorded the second lowest extreme low temperature index value ever.

“We continue to see an increase in historically unusual weather and an inexorable increase in sea levels,” Actuaries Institute Climate Risk Working Group convenor Rade Musulin said. “Flooding has replaced fire as the main hazard affecting property. We need to continue our focus on future-proofing our building stock.”

Heavy rainfall during March 16-23 in NSW caused significant flooding, killing five and leaving a damage bill of around $1 billion. The index notched up its fourth highest extreme rainfall value for the East Coast South cluster, which covers eastern NSW, including Sydney.

Other clusters in south-eastern parts of Australia also exhibited very high levels of rainfall.

From March 18-24, water storage in the Greater Sydney dams increased by 6.2 percentage points or almost 160,000 millilitres, enough water to supply the area for 124 days.

The sea level index continued its rising trend with all clusters recording a positive value, and the Rangelands North region recording the highest ever sea-level index value.

The index tracks changes in temperatures, precipitation, dry days, strong winds and sea levels across a dozen Australian regions that are climatically similar.