The Actuaries Institute’s latest quarterly climate index shows the East Coast South region - which covers Sydney and most of the NSW coast - set a record for extreme rainfall in winter.

The Wet Tropics region, which includes northern-most Queensland, notched up the Australian Actuaries Climate Index’s second highest value for extreme rainfall since it began in November 2018.

The update comes as the number of claims insurers have received related to the flooding catastrophe since October 12 rose to 13,160 and Sydney experiences its wettest ever year. Earlier this month, the rain gauge at Observatory Hill broke the previous annual rainfall record of 2194 millimetres set in 1950, and there has been substantial wet weather since.

Institute CEO Elayne Grace says the latest index readings show extreme climate variations are continuing, increasing the urgency to reduce greenhouse gas emissions.

“The frequency of extreme weather events and natural disasters across the country in recent years highlights the need for collaborative and urgent action to improve resilience,” Ms Grace said.

Bureau of Meteorology models indicate current La Nina conditions will persist until early next year, when neutral conditions will return. After declaring an end to La Nina in mid June, the Bureau said a third La Nina was in effect just months later.

“After seven consecutive months of ... a La Nina phase, Australia experienced a brief reprieve in the months of July and August,” Chair of the Actuaries Institute Climate Risk Working Group Rade Musulin said. “Australia re-entered a La Nina phase at the beginning of September which will likely bring another spring and summer of higher-than-average rainfall, especially on the east coast.”

The index’s winter values for the southern slopes of Victoria and Tasmania and Murray Basin clusters reflected an unusual cold front in south east Australia in July. That led to snow settling as low as 150 meters above sea level and severe frosts.

This resulted in Australia’s mildest value for extreme warm temperature since 2012.

The institute launched the index in 2018 to measure extreme weather conditions and changes to sea levels. Quarterly updates are based on six components measuring changes in the frequency of extreme high and low temperatures, heavy rainfall, dry days, strong winds and changes in sea levels across 12 Australian regions that are climatically similar.