FORECAST: Mixed bag of weather this week for the Northern Rivers. =
FORECAST: Mixed bag of weather this week for the Northern Rivers. = Higgins Storm Chasers

Forecast: Unsettled weather in store as winter approaches

THE official start of winter may be just 10 days away, but the Northern Rivers is in for some warm weather - and even the chance of a thunderstorm - this week.

There will be a few good days for beachgoers, a couple of damp days and some cold nights. And we could see a return of something that has been lacking this year - a thunderstorm.

Sea surface temperatures on the east coast are resting at a comfortable 24-26C, and daily maximums of up to 25 degrees are forecast during the week as above-average autumn temperatures wind to a close.

For Byron Bay, overnight temperatures are predicted to fall 11-14 degrees, with daytime temperatures reaching the low to mid 20C.

There is a chance of a shower or two Thursday and Friday, where the forecast predicts a medium -50 per cent - chance of showers along the coastal fringe, slight - 30 per cent - chance elsewhere, and a chance of a thunderstorm in the morning and afternoon.

Drizzly conditions are in store for Lismore, but by the weekend the sun will be back out and bringing above-average temperatures of 25C, Saturday to Monday.

While warm during the day, the nights will tell a different story with temperatures threatening single digits.

Overnight temperatures will sit around 11 from now to Friday, dropping to 10C on Sunday and Monday.

According to the Bureau of Meteorology, a high pressure system over the Tasman Sea is slowly drifting east, maintaining a ridge over much of the state.

"The dominance of the ridge will bring generally warm and dry weather conditions over the next few days, although the presence of an inland trough in the state's far west may bring some chance of thundery showers in parts of the far western districts today", according to the BoM.

"The inland trough is forecast to weaken by Thursday as the ridge strengthens over the state again, before the next front that looks set to cross the state towards the end of this week, that will bring cooler changes across the state by the beginning of the new week."

The mean minimum temperature for Lismore in May was 9.8C, and the maximum 23.4C.

The mean minimum temperature for Ballina was 12.1C, and 22.5C the average maximum.