As our sodden and flood-weary country emerges from three long years of La Nina, there’s a different threat looming just over the horizon.

Firefighters know that “grass fires follow floods”. The grass and forest regrowth that springs up so quickly during rainy seasons, even in areas that are normally almost bare, quickly dies and dries out when the weather turns, becoming tinder-dry fuel for bush and grass fires.

Make no mistake, while grass fires are less intense than forest fires, they can be just as dangerous. They can start mere hours after rain stops, and often spread at breakneck speed, too fast for people to outrun. Many people have been killed when trapped in the open or in cars by fast-moving grass fires.

Their spread can be highly unpredictable and catch communities unaware. In my 51 years as a firefighter with Fire & Rescue NSW and as an RFS volunteer, I’ve sometimes been caught out when a sudden wind change sent a raging grass fire in an unexpected direction. They’re volatile: difficult to predict and hard to tame.

As the rare, protracted La Niña wanes, and we return to hot and dry conditions, vast swathes of the drying landscape are becoming a powder keg, with millions of hectares of grassland, as well as forests, primed to burn. All it takes is a lightning strike, a carelessly tossed cigarette, or a harvesting accident to spark disaster.

Previous protracted La Niña events give us a sense of just how bad things could be, with three similar events since the 1950s in Australia: 1954–1957, 1973–1976, and 1998–2001. During each of these periods there was prolific growth, followed by extensive grass fires in inland areas, immediately followed by major forest fires causing loss of life and property on the east coast. Homes were lost in the Blue Mountains and Sydney suburbs in 1957, 1977 and 2001/2002.

On January 8, 1969 – following a double La Niña – hundreds of fires fanned by high winds broke out and destroyed 230 houses and 21 other buildings in Victoria. A fast-moving grass fire near Lara unexpectedly changed direction and engulfed a freeway, catching drivers by surprise. Tragically, 17 people who ran from their cars were killed.

Our most widespread grass fires on record were in 1974-1975, in the middle of a prolonged La Niña event. I was 16 years old at the time, and vividly remember my mum, dad and I struggling to find our car through thickets of two-metre high grass while on an outback camping trip in NSW where we expected to find red desert.