Analysis of the occurrence of days of heatwaves at Canberra Airport from 1939 to 2025

[Gavin O'Brien]

Hi everyone,

I have just completed an analysis of the number of heatwaves observed at the Canberra Airport Meteorological Station from1939 until last Summer (October 2025 March 2026).

collated in Excel format the number of days above 38 degrees, then days > 40 degrees and totaled both for each month/year.

There were no heatwave days (>38 degrees) recorded in October or April at the site. 

It wasn't till November 1980 that the site recorded a day over 38 degrees in November, with just 5 days in total from 1939.

The first December day over 38 degrees was in 1945, with just 3 days until 1972. December ,1994 recorded 3 days for that month, with no days since 2012.

January is the standout month for heatwaves in Canberra. The first day over 38 degrees was in January 1942. January 1968 recorded the first 2 days over 38 degrees. The number of multiple days over 38 degrees ramped up from 2001 with 9 days observed in 2014.

The January of 1968 was the first recorded month when the maximum temperature exceeded 40 degrees. 1973,1998 and 2007 followed. January 2013 experienced 2 days followed by 2014 with a record 6 days followed by 2019 with 5 days. The years from 2013 to 2026 account for 19 days exceeding 40 degrees. Last Summer's January had 3 days over 40 degrees in a La Nina year.

February saw its first >38 degree day in 1942 with just 8 days until 2009, when there were 4 days that year, with a further 4 days in 2017 and none since.

March had one day over 38 degrees in 2023.

What is startling is the increase in extreme temperatures in recent decades. Canberra Airport is around 580 metres above sea level. The trend is upwards and with an El Nino Event underway one wonders what the Summers of 2026/27 and 2027/8 are likely to bring to Canberra and the surrounding region.

With a declining rainfall and extreme rainfall events followed by "flash droughts", the coming fire season looks a bit like the current Northern Hemisphere experience. 

Cheers,

Gavin