BIG CHILL: Northern Rivers residents are in for another blast of winter next week.
BIG CHILL: Northern Rivers residents are in for another blast of winter next week. Tessa Mapstone

THE BIG CHILL: Severe frost, freezing temps on way

WHILE it's been quite mild, don't be too hasty in packing away the winter woolies yet as the warm weather is set to move aside for a significant cold front bringing below average winter temperatures to the region.

There is an extreme risk of widespread frost inland on the Northern Rivers on Monday as minimum temperatures drop to -1C in Lismore and -2C in Casino.

Lismore's long term mean minimum temperature for August is 6.7C, and 7.2C in Casino.

Along the coast in Ballina and Byron Bay overnight temperatures are predicted to fall to between -1C and 5C with daytime temperatures reaching between 19 and 22C.

These overnight temperatures are well below Byron Bay's minimum August average of 13.1C, according to weatherzone.

The Bureau of Meteorology forecaster Rebecca Sarr said there was a reasonably cold front passing through the south of NSW.

"Along with the cold front it brings an area of cold air behind it which does affect the whole of NSW,” Ms Sarr said.

"Lismore isn't seeing any rainfall from this front but the cold air moving up behind the front is what is being seen with the cold temperatures on Monday.”

She said temperatures from now until next week will gradually decrease.

"We are seeing a general trend of temperatures decreasing over the weekend into Monday.

"And then we have another high pressure system push through behind the front and we will see temperatures gradually begin to rise over the early parts of next week.”

Ms Sarr said as soon as the bureau forecasts temperatures down to 1-2C as the overnight minimum, it was likely you'll see frost around.

"The temperature we forecast is the two metres above the surface and it can be several degrees or more colder at the surface where the frost is forming.

"In general across the state following the cold front we will see overnight minimums broadly below average.

"It will be around 2C below average in most parts of NSW and then even more in the north-east of the state, around 4C or so.”

Sunny conditions with daytime temperatures reaching between 19 and 22C across the region on Monday before minimum and maximum temperatures warm a few degrees as the week continues.

BoM currently forecasts daytime temperatures from Tuesday next week in the low to mid 20s.