NSW will this week sweat through its first heatwave of the season, prompting a warning from fire and health authorities.
Temperatures in Sydney are set to reach the mid- to high-30s by Friday, and more than 40C in regional areas.
The Bureau of Meteorology's Jake Phillips said it was the first heatwave of the season and, while it won't be very intense, it could impact people more than normal given the recent run of mild conditions.
"One of the characteristics of heatwaves is not just hotter maximum temperatures but also hotter minimums," he said in a statement on Wednesday.
NSW Ambulance chief superintendent Alan Morrison urged people to take extra care and avoid the heat, especially children and the elderly.
"Heat can kill which is why it's so important to stay hydrated and look out for the elderly the young and pets," he said.
Paramedics treated nearly 4500 people for dehydration between December 2017 and March 2018, and hundreds more for heat exhaustion.
© AAP 2018
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