People are being urged to take immediate precautions as a prolonged heatwave blankets much of the country this week, with health experts warning the conditions could be deadly if underestimated.

The Royal Australian College of General Practitioners (RACGP) has advised people to prioritise hydration, remain indoors during the hottest parts of the day and regularly check on vulnerable family members, neighbours and friends.

The warning follows advice from the Bureau of Meteorology, which has forecast a multi-day heatwave affecting more than half of Australia, with temperatures expected to exceed 45 degrees Celsius in some areas and significantly elevate fire danger.

RACGP president Michael Wright said extreme heat posed serious and sometimes fatal health risks.

“Heat waves can be deadly, and the Bureau of Meteorology has warned that this promises to be the ‘most significant’ heatwave south-eastern Australia has seen in six years,” Dr Wright said.

“My advice for all Australians is to drink plenty of water, try to stay indoors if possible during those peak UV hours of 11am to 3pm, and remember to ‘slip, slop, slap’, It’ also important to check in on friends and family members who are more vulnerable to the impact of heat waves, including older people.”

Dr Wright warned against complacency, noting that heatwaves have caused the highest number of extreme weather-related hospitalisations over the past decade.

“Almost one third of hospitalisations relating to extreme heat occur in people aged 65 and over,” he said, adding that infants, pregnant or breastfeeding women, people with chronic illness and those unable to escape high temperatures were also at heightened risk.