New South Wales is set to swelter through the last days of the year, with an extreme heatwave affecting parts of the state.
Penrith is expected to hit a maximum of 42 degrees today, after parts of Sydney's west endured 37 degrees yesterday.
Bureau of Meteorology duty forecaster Neale Fraser said it would be a few degrees cooler in the CBD, where a sea breeze expected around 1pm is expected to cap temperatures at 37 degrees.
But it could be hotter elsewhere across the city, he said.
"Forty degrees (is forecast) for most of Sydney and then right on the coast the sea breeze might keep it down to low to mid 30s," he said.
https://twitter.com/BOM_NSW/status/813506599155331072
An extreme heatwave on and east of the ranges and the mid north coast is expected to move north over the weekend.
A very high fire danger is also forecast for Sydney today.
The heatwave has prompted NSW Health to issue warnings, especially in the north where a slow moving cool change is not expected to hit until Monday.
https://twitter.com/BOM_NSW/status/813851283459346432
People are urged to stay hydrated, avoid alcohol and limit physical activity.
Surf Life Saving NSW is also asking people to apply sunscreen and seek attention from lifeguards if they experience signs of heat stress, such as excessive sweating, rapid heart rate and nausea.
With AAP.