Sub-zero minimum temperatures were recorded in seven of the eight Australian states and territories overnight, with only the Northern Territory failing to record a freezing temperature.

On Wednesday morning, the coldest reading for each state and territory was:

NT: Alice Springs 3.2°C

SA: Yunta -0.9°C

Qld: Applethorpe -1.1°C

TAS: kunanyi/Mt Wellington -1.5°C

WA: Newdegate -1.5°C

ACT: Tuggeranong -2.8°C

VIC: Mt Hotham -3.1°C

NSW: Thredbo Top Station -6.5°C

What caused the widespread overnight chill?

These were not exceptional or record-threatening temperatures for midwinter, but they were still well below average in many locations.

For example, Newdegate in Western Australia’s Great Southern region – which fell to -1.5°C overnight – has an average July minimum of 4.4°C and a record July low of -3.8°C. 

Thredbo Top Station – which recorded Australia’s lowest reading of -6.5°C overnight – has an average July minimum of -5.1°C and a record low of -13.5°C.

Minimums were cooler than average across a broad area of the country due to:

Calm, clear, conditions caused by a strong high pressure system centred over southern SA

A cold dry airmass lingering in the wake of a series of cold fronts which have now moved well out into the Tasman Sea

Will the cold nights continue this week?

The alpine region of NSW and Victoria can expect a string of nights well below zero lasting all the way through to the end of the week. That’s good for the snowmakers at the ski resorts.

READ MORE: How does snowmaking actually work?

But many other locations in the southern half of Australia might just have shivered through the week’s chilliest morning.

We wrote yesterday about the impending period of very heavy rain likely in northern NSW, while several days of showers can be expected between Thursday and Monday for the stretch of the east coast from at least Sydney to Brisbane.

While this rainfall event will be very much confined to the coast and adjacent ranges, the moist easterly flow will push a fair way inland, increasing the relative humidity which in turn will prevent the mercury from dropping too far overnight.

The map above shows precipitable water in the atmosphere and the predicted position of the high centred over South Australia on Thursday morning. Winds circulating anti-clockwise around the high will push maritime air to inland regions, even though rain is only expected near the east coast.

Meanwhile in Western Australia, a cold front approaches the southwest. While it will introduce a cooler, moister airmass, minimums should generally be warmer than they have been in recent days at many locations due to the cloud and extra humidity.