A severe fire danger rating was issued for the greater Sydney region on Sunday, while much of the rest of the state has a “very high” rating.
Total fire bans are in place for Sydney and the Hunter region.
The New South Wales Rural Fire Service warned residents to prepare their bushfire plans. If people are considering leaving their homes they should leave early, the RFS said.
Temperatures hit 43.4C at Sydney’s Observatory Hill just after 1pm.
The Bureau of Meteorology said cooler conditions were expected to reach coastal areas during the afternoon and Sydney’s west in the evening.
NSW Health warned people to drink plenty of water and limit their time outdoors because of a rise in ozone pollution as a result of the hot, still weather.
Sydney was forecast to have poor air quality on Sunday, which can especially affect people with asthma and chronic obstructive pulmonary disease.
“Ozone levels are higher outdoors than indoors, so limiting time outside during the heat of the day and in the evening would help people to keep cool and to limit their exposure to ozone pollution,” the environmental health director, Dr Ben Scalley, said on Saturday.
Scalley also warned of the dangers of a heatwave, which puts strain on the body, can cause dehydration, heat exhaustion and heat stroke.
The NSW police deputy commissioner Catherine Burn said the state’s heatwave plan had been activated to ensure a coordinated response from emergency services.
She reminded people it was an offence to leave children or pets in vehicles. “Cars become a furnace very, very quickly in this type of heat.”
Surf Life Saving NSW has implored people heading to the beach to take care given there have been 10 drownings since the beginning of December.
A 48-year-old is fighting for his life after he was found face down in the water at Sandon Point Beach on Saturday.
In a separate incident, a 35-year-old man was taken to hospital in a stable condition after being pulled semi-conscious from the Hawkesbury river at Lower Portland.
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