A high pressure ridge cleared skies and a cool air mass created the perfect conditions for temperatures to drop well below the monthly average in parts of New South Wales.
Taree on the Mid North Coast dropped to 8.1 degrees overnight, its coolest December night in 15 years and eight degrees below the monthly average.
Scone has only felt one night so far this month above 11 degrees, averaging 5.4 degrees below the December average.
Walgett in the NW Slopes and Plains has felt temperatures drop to below 11 degrees over the last three nights, keeping well below their December average of 18.3 degrees.
Further west, Parkes hasn't seen one night exceed six degrees over the last three evenings, remaining well below the 14.4 degree December average.
A low pressure trough and warm air mass will raise overnight temperatures this evening for the majority of the state. Southern areas of the NSW will see overnight temperatures increase up to eight degrees from last night. However, as the trough passes over the state and a cool air mass follows in its wake, evening temperatures will drop back to below average in southern areas.
© Weatherzone 2013
17:37 EDT Much of western New South Wales has begun a heat wave, reaching at least five degrees above average for at least five days, averaging a maximum of 35 degrees or more.