It is believed the fire, which was downgraded from Watch and Act to Advice yesterday morning, was caused by harvesting machinery.

RFS Liverpool Plains District co-ordinator Myles O'Reilly said the incident was one of seven in the district during what was a high risk weekend.

"A lot of the fires were grassfires, but most of those fires have been put out, we only have three left on the books," he said.

"We have had a number of grassfires associated with the use of plant harvesting over the past couple of weeks, so it's unfortunately becoming a common issue, not just here, but across the state."

A Total Fire Ban is in place today for the Northern Slopes and North Western area, which includes Gunnedah Shire with a Very High fire danger rating.

Approximately 100 hectares were lost during a grassfire on Sunday burning near Quirindi on Knights Road.

There are two fires on patrol in the Gunnedah and Liverpool Plains districts today, the most notable a hayshed fire south of Carroll near Piallaway which started last Friday and is still burning.

Conditions are expected to worsen into Tuesday and Wednesday with temperatures predicted to hit 42 degrees before a cooler change on Thursday which will continue into the weekend.

"The weather is variable, at the moment we have a total fire ban in the Northern Slopes which covers Liverpool Plains and Gunnedah Shire, we are a fire danger rating of Very High and to be perfectly honest Very High during the fire season is the space that we operate in most of the time anyway," Inspector Myles said.

"Even though the conditions aren't quite as bad as they were yesterday we are expecting them to worsen tomorrow and Wednesday but we are hoping, given the projections, that towards the weekend they will start to drop back down again.

"We are hoping that from the weekend onward it will drop back down again but it's only going to be a matter of time before it picks back up again to very high danger ratings."