Locals should prepare themselves for severe thunderstorms after the Bureau of Meteorology (BoM) issued a warning on Thursday afternoon.
The storms are likely to produce heavy rainfall that may lead to flash flooding, damaging winds and large hailstones in the warning area over the next several hours.
Inverell, Armidale, Tamworth, Gunnedah, Narrabri and Coonabarabran could all possibly be impacted, according to the BoM.
The State Emergency Service (SES) says locals should move their cars under cover or away from trees, and to secure or put away loose items around the house, yard and balcony.
They should also keep clear of creeks and storm drains and avoid flood waters, and keep at least eight metres away from fallen power lines or electric fences.
It's advised computers and appliances should be switched off and people should avoid using the phone during the storm.
For emergency help call the SES on 132 500 or emergency services on 000.