Local health authorities warn that high temperatures early in the season can affect people's wellbeing because they are not yet acclimatised.

With some parts of the south-west expected to reach 42 degrees, the Murrumbidge Local Health District (MLHD) has issued a heat alert, urging people to take the risk of heat-related illness seriously.

MLHD director Tracey Oakman said while heat-related illness may affect anyone, over-75s, infants and children, people with a chronic medical condition and people who live along are are particularly vulnerable.

"Every year hot weather and heat waves cause illness, hospitalisations and sometimes even deaths."

During a heat wave, it is important to stay in regular contact with your elderly friends, neighbours and relatives, and to look out for other vulnerable members of your community.

"Heat puts a lot of strain on the body and can cause dehydration, heat exhaustion and heat stroke. It can also make underlying health conditions worse. However, being prepared and taking some simple precautions can reduce the risk of heat-related illness," said Mrs Oakman.

These simple precautions will help people minimise their risk of heat-related illness:

Drink plenty of water, and remember to carry some with you when you're out and about.

Avoid alcoholic, hot or sugary drinks.

Plan your day around the heat. Stay indoors between 11am and 5pm and minimise physical activity.

Keep the sun out of your house by shading windows with an awning, shade-cloth or plants. Shutting curtains will also help.

Don't forget your pets - ensure they have shade or bring them inside, and make sure they have plenty of water