These events are times of abnormally hot weather lasting several days.
Climate projections show extreme heat events are occurring more often and with greater intensity.
It is important you prepare early, plan for the first heatwave and protect yourself.
NSW Health offers the following tips.
Prepare early and plan for a heatwave
• Monitor the weather using Bureau of Meteorology's Heatwave Service - www.bom.gov.au/australia/heatwave/.
• Prepare yourself and your home before the heat arrives. Use the heatwave checklist at www.health.nsw.gov.au/environment/beattheheat/Pages/heatwave-checklist.aspx.
• Know who to call if you need help.
• Follow your doctor’s advice if you have any medical conditions.
Keep yourself cool
• Wear loose fitting clothing.
• Stay out of the sun.
• Try to be indoors during the hottest part of the day.
• Close windows and doors to keep the heat out.
• Use air conditioning.
Stay hydrated by drinking water
• Avoid alcoholic, hot or sugary drinks including tea and coffee (they can make dehydration worse).
• If you go outside, carry a bottle of water with you.
Look out for each other
• Keep in contact with elderly friends, neighbours and relatives during a heat wave in case you or they need help.