With elevated fire danger levels predicted in certain regions until the end of April, researchers at Scion are calling for greater public awareness about the hazard posed by tinder-dry grasses.
The fire hazard posed by cured (dry brown) grass is quick ignition and a fast-moving fire.
The fire season is generally October to March but dry conditions in northern and eastern parts of the North Island, Wairarapa, Marlborough, Canterbury and Otago are keeping fire authorities on alert.
Dry conditions have created low soil and fuel moisture levels and, with high pressure favoured for at least the first half of April, these same parts of the country are expected to further cure (brown off) grass.
As curing increases, the moisture content decreases further, making grass easier to ignite and more likely to burn with higher rates of spread and intensity.
Fire and atmospheric science team researcher Shana Gross said it is important for the public to know that dry grasses are still highly flammable at this time of year, even though temperatures have dropped.
“Grass is one of the most common fuels in New Zealand,” she said.
“It’s super abundant and can ignite quickly, spreading fast. People need to think about grasses, tussock, and grazed and ungrazed pasture (that is dry and/or isn’t irrigated), as a potential fire hazard and be aware of the elevated risk to property and lives when grass is very dry.”
Over the past 30 years, data shows that most wildfires in NZ started in grass fuels. Of the 50,097 wildfires recorded, 40,736 or 81% of wildfires started in dry grass.
Based on the predicted weather conditions for the next couple of weeks, a grass fire could spread 8km per hour on the flat and even faster uphill.
“Of all the fuel types, fires travelling in grass fuels are a major cause of firefighter injuries or fatalities due to people underestimating how fast grass fires can travel,” Gross said.
Education plays a pivotal role in reducing fire risks, with Scion advocating for public awareness and proactive measures that encourage people, especially in rural areas or in semi-rural subdivisions, to think twice before engaging in activities that could generate sparks near cured grass, such as mowing tall brown grass, which can cause a spark and ignite a fire.
Best practice is to reduce activities that creates sparks.
“Anyone cutting through stubble or long grass using mowers, chainsaws or brushcutters needs to be aware about the current fire danger level and other conditions before starting. Fire and Emergency New Zealand provides a handy website to make checking easy,” Gross said.
