It’s heating up again in Greater Sydney | MAP

Temperatures are set to soar across the Greater Sydney region tomorrow, January 13.

According to Weatherzone, the mercury will will peak in the mid to late 30s in most places across Sydney on Friday.

The temperature will reach 40 degrees in the Hawkesbury and Penrith.

(Below is a heat map showing the expected temperatures across Australia at noon on Friday):

It has been a testing week weather wise across the Greater Sydney region.

The temperature peaked on Wednesday, with some areas across NSW experiencing their hottest day in three to four years.

The heatwave continued across most areas of the state on Thursday, but there was some relief for people living along the coast.

The recent spate of hot weather has prompted warnings from health experts about the long-term effects of a heatwave.

NSW Health director of environmental health Ben Scalley said a small amount of people suffered from heat-related conditions during this period.

Mr Scalley said a large number of patients suffered from heart attacks during heatwaves, while there was an increase in kidney-related conditions.

A rise in temperature can also signal flare ups for people suffering from asthma.

The rising temperatures can also provide concerns for the state’s fire fighters.

The NSW Rural Fire Service (RFS) has predicted the potential for fires will rise again on Friday.

The NSW RFS issued a total fire ban for the Greater Sydney region on Wednesday.

Further total fire bans are expected to be issued across the state on Friday.

The beach, river or swimming pool will again be tempting for residents as the hot weather continues tomorrow, January 14

The temperature is set to be in the low to mid 30s on Saturday, peaking at 35 degrees in Penrith.

On Sunday, the weather is set to fall to the mid to late 20s in most places across the Greater Sydney region.