Major bushfires are burning across multiple regions in northern NSW where extreme fire danger ratings are expected to be in place for days.

A total fire ban was in effect on Thursday in the northern slopes and north-western regions, near the Queensland border, as 77 fires burned across the state.

More than 900 NSW Rural Fire Service personnel had been deployed to monitor and battle fires in the dangerous conditions.

A blaze is being closely monitored in the Nymboida area, 30km southwest of Grafton, after an emergency warning was issued on Wednesday afternoon.

The threat level was later downgraded, but the bushfire was still burning out of control on Thursday morning after covering more than 3475ha.

Other keenly watched fires include a 1600ha blaze on Thunderbolts Way, near Gloucester, and a fire that has scorched 1470ha of the national park east of Tenterfield.

Also under watch are blazes west of the Kempsey region.

A fire in Willi Willi National Park and surrounding areas has burnt more than 29,500ha and is being controlled.

The second bushfire is burning in the Lower Creek area north of the Macleay River, 50km northwest of Kempsey.

RFS operational officer Emilie Koek told AAP there was an elevated fire danger over the coming days.

“Potentially over the weekend conditions could ease, but we will have to see how the forecast pans out,” she said on Wednesday.

A recovery centre is open in Willawarrin as of Thursday morning for bushfire-affected residents in and around the Kempsey region who are able to leave and seek shelter.

A cold front has brought a major change to weather conditions, including a 10-15C drop in temperatures for many parts of the state on Thursday compared with highs earlier in the week.

While conditions may have eased overnight, fire services are wary of lightning strikes worsening current fires.

Investigations continue into several bushfires on the NSW mid-north coast that are believed to have been deliberately lit.

– AAP