Spring was Australia’s seventh consecutive season of extreme dryness and laid the foundation for this summer’s tragic bushfire crisis, the latest Australian Actuaries Climate Index reveals.

All 12 Australian regions which make up the index recorded above average highs in temperature and below average rainfall when measured against the three decades to 2010, the reference period for the index. Several regions broke records.

“We have all seen the devastation of the summer: terrible bushfires, followed by regional hailstorms. The index records the factors that we know can lead to incredible damage among communities,” Actuaries Institute CEO Elayne Grace said.

The fires have so far ripped through more than 11 million hectares, killed more than 30 people, destroyed more than 2400 homes and devastated wildlife populations. Nationwide losses for the catastrophe season, including hail and bushfire, have topped $2.3 billion, the Insurance Council of Australia (ICA) says, and the states are now evaluating Prime Minister Scott Morrison’s proposal for a royal commission into the fires.

Every region except Tasmania recorded more consecutive dry days in spring than the reference period average, the latest index shows. Particularly high numbers of consecutive dry days were seen in parts of NSW, Queensland and across large swathes of central Australia.

The latest index showed parts of west and southern Australia breaking records for extreme high temperature. The nation has not avoided above average extreme high temperatures since 2012.

Higher than normal atmospheric pressure also led to increased wind gusts during spring, especially in the south east, and this combination of dry, hot, windy weather fuelled the devastating summer bushfires, the Institute says.

The quarterly index is collated at the end of each season. Weather data is grouped into 12 climatically consistent regions and each season is compared to the same season in previous years and against a reference period of 1981-2010. This reveals changes in temperatures, precipitation, winds and sea levels.

The index is intended to support assessment of the change in risk for general insurers, banks and investment managers. The Institute intends to publish additional indices in the future measuring specific risk, for example the risk of damage to property and health, and the risk of excessive energy demands.