The Actuaries Climate Index (ACI) has recently been updated. The five-year average has slightly decreased since the last update in the fall. It now stands at 1.15, compared with an average of zero over the reference period from 1961 to 1990. 

The ACI measures the variation of extreme weather conditions and sea level in Canada and the United States. The farther the ACI averages deviate from zero, the more extreme weather events and sea level rise are pronounced. 

The updated data for August 2023 was made public on February 12. 

In the previous quarterly update, which covered Spring 2023, the average value was 1.17 for Canada and the United States. Over the past five years, the highest value of the Index was 1.23, on two occasions.

Since the summer of 2018, the five-year average has consistently exceeded the value of 1, with the trend increasing each quarter. The ACI's moving average in the summer of 2022 was 1.16. 

The variations of the index measured for the same season remain significant. From 2018 to 2023 for the summer season, the Index was at its lowest in 2019, at 1.2, and its highest in 2021, at 2.3. In 2023, the seasonal ACI for the summer was 1.4. 

In its latest summary, ACI analysts explain that over the last 20 years, the prevalence of mostly warmer or hot temperatures, fewer cool or cold temperatures, a rise in sea level, more heavy precipitation, and more droughts have had an upward effect on the index. 


To determine this index, variables that have the most impact on the population and the economy are used: high and low temperatures, heavy precipitation, droughts, strong winds, and sea level. 

The ACI was launched in 2016 by four organizations associated with the actuarial profession in Canada and the United States.