The Northern Rivers area (where Lismore is) has a lot of gullys and valleys, whereas the towns there tend to occupy flatter areas. Winter in the gullys gets bloody cold. The official temperature in Lismore is measured at the Post Office. I grew up in the Northern Rivers, and saw frost most years in the gullys and on the slopes of our farm. We were closer to the coast than Lismore, so they'd get more frosts than we did.