Although it will mostly be a pupil-free day for the majority of schools in the state, school staff across NSW will be going to work in the biting cold. In Sydney, morning commuters traveling from further inland will likely wake up temperatures well below freezing and frost on the ground. Places like Camden and Badgerys Creek could cool to as low as -5 degrees. The city itself could cool to just below 5 degrees, the second time this month and exactly a week since the minimum temperature dropped below five degrees at Observation Hill. Elsewhere in the state and ACT, places like Armidale, Orange and Canberra are also expected to plunge to around -5 degrees, while various places over the interior from Tamworth to Bega could cool to between -3 and -1 degrees. Temperatures this cold are associated with clear overnight skies, brought about by a high pressure system situated over the eastern parts of the country, and a lingering cold airmass in the wake of recent cold fronts that have affected the region in recent days. Increased overnight cloud cover ahead of a cold front with onshore winds along the coast should bring warmer early morning conditions from Tuesday.