Development and verification of thermal stress forecasts for cattle in Australia's Rangelands

Development and verification of thermal stress forecasts for cattle in Australia's Rangelands

The highly variable weather and climate of northern Australia can pose a significant threat to cattle and other
livestock, with prolonged heat waves and sudden chill conditions known to increase mortality risk. For example,
the compounding impact of high temperatures, high humidity and calm conditions led to significant cattle heat
stress and dozens of animal deaths in southern Queensland in late January 2024. Conversely, the combination of
flooding, low temperatures, and high winds associated with a tropical low caused thousands of cattle deaths in
northern Queensland in February 2019.
Currently, the Australian Bureau of Meteorology issues national sheep graziers' alerts for potential risk of chill
Test and exposure, however there are no such equivalent chill (or heat) warnings for cattle. A key objective of the
Northern Australian Climate Program (NACP) is to develop prototype forecast products of thermal stress that can
be utilised by livestock producers to help manage the risks posed by extreme weather and climate events.
In this research, we describe NACP's latest prototype forecast maps of the Heat Load Index (HLI) and Cattle
Comfort Index (CCI), derived from the Bureau's numerical weather prediction system - ACCESS-G3. These
forecasts display the predicted chill and heat conditions across Australia out to 7 days. We also assess how well
the predictions of CCI performed for a extreme heat event in southern Queensland in January 2024.