NSW just had its quietest bushfire season in a decade, with flames claiming less than one percent of the area that was lost during the state's previous 'Black Summer' fire season.

According to NSW Rural Fire Service Commissioner Rob Rogers, this season "firefighters have responded to just over 5,500 bush and grass fires burning 30,963 hectares across NSW."

These numbers are considerably smaller than the previous season, which saw 11,400 fires scorching 5.5 millions hectares of land in NSW alone. 

The stark contrast between the last two bushfire seasons comes down to the climate drivers that were influencing the weather in NSW.

The 2019/20 bushfire season was exceptionally hot and dry and it came at the end of a multi-year drought in NSW.

The weather of that infamous season was underpinned by neutral conditions in the Pacific Ocean, a strong positive Indian Ocean Dipole (IOD) and a prolonged negative phase of the Southern Annular Mode (SAM). Both the IOD and SAM contributed to the heat and lack of rain in NSW during late 2019 and early 2020. At the same time, the neutral Pacific Ocean failed to deliver much-needed rain that is more common during La Niña.

Fast forward to this bushfire season and the state of climate drives influencing Australia's weather had changed dramatically.

La Niña was active in the Pacific Ocean from late-September 2020 to late-March 2021. Throughout this time, the IOD remained neutral in the Indian Ocean and the SAM was almost always in a positive phase. This mix of climate drivers allowed La Niña to boost rainfall and suppress daytime heat in NSW, without any competing influence from the IOD or SAM.

As a result, NSW had its wettest and coolest summer in nine years and only saw total fire bans on 11 days during the 2020/21 season. This was a big drop from the 60 fire ban days in the 2019/20 season.

Despite less fires, the Rural Fire Service was kept busy in March assisting communities affected by flooding across NSW.

Looking ahead, it's too early to know what the next bushfire season will bring for NSW. Firefighting agencies and landholders will now spend the next few months carrying out hazard reduction burns across the state, in an effort to reduce bushfire fuel loads before the next season begins.