Narromine residents will be hit by the full force of summer today with temperatures to sizzle into the 40s.

There is an extreme UV?rating around the region today with the Trangie weather station expecting a scorching 42 degrees and a low of 21 degrees.

Narromine swimming pool is expected to be a popular place.

"The coolest place to be is Narromine Pool," Aquatic Manager, Val Bollard said.

"We've been busy since opening. We had a record number of people through on our first day, around 80."

Val asked people to be responsible in today's heat.

"Slip, slop and slap," he said, "and drink plenty of water''.

NSW Ambulance is also urging people to take care to beat the heat.

Paramedics advise hot weather can lead to heat exhaustion and life-threatening situations for people who do not manage their health.

"Dehydration, sunburn and heat exposure can lead to heat stroke," a NSW Ambulance spokesperson said.

"People working in excessively hot environments, such as roof cavities, can suffer a rapid escalation of body temperature which can lead to death. Dehydration in the frail can lead to confusion and falls."

They advise to be alert to the symptoms of heat exhaustion including nausea, vomiting, fainting, dizziness, loss of appetite, weakness and or headache.

The NSW Rural Fire Service has urged grain growers to cease harvesting crops.

Superintendent Lyndon Wieland said farmers could prevent fires from igniting during the period of increased risk.

"Using harvesting or farm machinery on days of increased risk can be very dangerous as sparks in dry crops can start fires that can spread very quickly," he said. "These fires have the potential to threaten property and also destroy millions of dollars worth of crops."

Farmers and other members of the community are encouraged to find a cool area and keep themselves well hydrated.

Mr Bollard said the pool was open from 6am-8am today for laps and would reopen from 1pm to 7pm. It opens tomorrow and Sunday from 10am to 7pm.