The Bureau of Meteorology expects a severe heatwave to spread across the state this weekend, with temperatures in the low 40s anticipated for the Western Plains region.

Conditions are expected to increase over the weekend and ease off mid next week.

The Western NSW Local Health District is urging people to take necessary precautions, and plan ahead for the high temperatures.

Walgett will top the chart, with a high temperature of 42 expected on Sunday 21 December, and 41 on Saturday 20 December.

Followed closely by Nyngan, Narrabri, Lightning Ridge and Coonamble, with temperatures expected to reach 41 degrees on both Saturday and Sunday.

NSW Ambulance advises individuals to stay cool, drink plenty of water, check on others and manage medication during heatwaves.

The Western NSW Local Health District is urging people to take necessary precautions with heatwave conditions forecast across the region.

"These extreme temperatures can cause life-threatening illness, so it is important to take action to stay cool and know the symptoms of heat-related illnesses," Western NSW Local Health District health director Ms Stanley said.

"If you are working outdoors take extra precautions to keep out of the heat in the hottest part of the day, wear a hat, take breaks to cool down, and stay hydrated."

More information can be found on the Bureau of Meteorology.