Today's forecast of 41C is just the beginning for Perth residents this week.
The maximum temperature is forecast to stay above 40C until Thursday when it is expected to drop to 30C.
The Bureau of Meteorology says thunderstorms are likely to develop at the start of the week but will clear by Wednesday when the temperature slips slightly.
With hot days and warm nights expected, the Health Department is reminding people of the risks associated with heat stress.
People over the age of 65 and children younger than two years are especially at risk, as well as women who are pregnant or breastfeeding, people with heart disease or high blood pressure, and those on certain drugs such as medication for mental illness.
People who work outside or who are not used to the heat, such as overseas travellers, may also be at a higher risk.
Although the human body can cope well in temperatures less than 32 degrees, higher temperatures can make it hard for the body to cool itself, the department says.
“The body loses heat by sweating, but when temperatures are consistently high, sweating isn’t enough to cool down adequately,“ the department warns.
The effects of heat stress can be mild and include muscle cramps, weakness and headache.
Medical advice should be sought if a person experienced high body temperature, nausea, dry hot skin or a rapid heart rate, the department said.
To avoid heat stress, people are reminded to remain hydrated, wear loose fitting clothing and stay indoors.
As at midday on Sunday the forecasts for the week are:Monday 25C-41C
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