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NSW, WA at risk of summer fires despite La Nina rains

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While most of Australia shows normal bushfire potential this summer, high grass and crop fuel loads in large parts of NSW and above average forecast temperatures in WA indicate above normal risk for those areas, according to AFAC, the National Council for Fire and Emergency Services.

Below normal summer fire risk is predicted in the ACT, Victoria, and some parts of NSW due to increased rainfall and areas burnt during 2019/20 fires, the “Bushfire Seasonal Outlook Summer 2021: Australia’s national picture of fire potential” report says.

The varied picture for locations across Australia comes after recent rainfall boosted soil moisture and stream flows across large parts of eastern Australia during La Nina conditions. After a wet spring, the summer outlook is also for above-average rainfall over eastern parts of Australia.

“Destructive and deadly fires can still occur during normal bushfire seasons across Australia. Fire potential can vary greatly, even at the smaller scale, between bordering states and territories,” AFAC said.

“In any season we could see periods of escalated fire danger and fires that require assistance from beyond the area from which they originate, especially if rainfall distribution through the period is not consistent.”

The outlook, which aims to assist planning, says above-median rainfall is likely for large parts of eastern Australia for December to February, while below average rainfall is more likely for parts of western Tasmania.

Maximum temperatures for summer may be above average for much of northern Australia and WA, Tasmania, and parts of western Victoria into southeast Australia and southwest NSW, while cooler daytime temperatures are more likely along the east coast of NSW into eastern Victoria.

There is a high chance minimum temperatures will be above the long-term average across most of Australia except for southern parts of WA into southwest SA.

Here is the summer bushfire outlook by state and territory:

NSW

The December to February outlook depicts above normal fire potential for large areas of NSW containing crop and grassland fuels through areas west of divide and in the Cooma Monaro. Significantly above average yields from crops are expected and delayed harvests could increase the risk high crop loads coincide with the peak of summer.

Along the ranges and coast, the likelihood of wetter than average conditions balanced the risk.

For areas east of the divide not affected by the 2019-20 fires, normal risk is projected.

ACT

The ACT fire potential in grasslands was pegged as normal and in forested areas, below normal fire potential is expected given a combination of fuel moisture conditions from increased rainfall and areas burnt in the 2019/20 fire season.

Above average spring rainfall, in particular during November, resulted in extensive rain soil moisture across the ACT and more above average rainfall throughout summer is predicted, and daytime temperatures are not expected to exceed median maximum temperatures.

Victoria

Average to above average rainfall in winter and spring, with the exception of the northwest and far west of the state, has resulted in a later start to the fire season than in recent years. Grassland and drier forests have been assessed as normal fire risk, although shorter-duration fires are still likely to occur on hot, dry and windy days.

Above normal pasture growth across paddocks and roadsides for much of the state would likely increase grass fire risk throughout summer, the report said.

Tasmania

The overall assessment is for normal fire potential for early summer, though the spring planned burning season has been difficult due to rain. Soil moisture levels are normal to above normal elsewhere, though the southwest is being closely monitored should rainfall deficits develop. Fuel conditions for the remainder of the state are considered only slightly below normal.

SA

Summer is likely to be characterised by days of peak fire risk to the community, with moderate conditions either side, and any return to widespread hot and dry conditions will quickly exacerbate fire risk. The coming three-month period is unlikely to be as wet as the preceding period, and grass fuel is likely to dry out. SA can expect to see grass fires as a key risk during the summer months, AFAC says.

Queensland

Soil moisture has recovered except in coastal and inland areas between the Fraser Coast and Mackay and the central coalfields. Milder conditions and the probability of above median rainfall across the state will likely result in increased soil moisture levels, promoting new grass growth, increasing future fuel loads and potential fire risk.

WA

Daily minimum and maximum temperatures are forecast to be above average across much of the state, and combined with above average grass fuel loads, produced an above normal fire potential for the Pilbara, Gascoyne and Murchison as well as for the Swan Coastal Plain, Jarrah Forest, and western most parts of the Esperance Plains and Mallee Bioregions. Normal fire potential is expected for the remainder of the state, including the far north where near average rainfall is expected.

NT

Normal fire potential is expected across all regions for the summer period, though if rainfall arrives late fire risk will be heightened. Significant rainfall has been recorded in some areas in Central Australia, though fire risk continues in localised areas which have not received rainfall.