After a mid-spring day as cold as this Monday across southeastern Australia, there were always going to be plenty of logs on the fire on Monday evening and lots of frost on the ground by Tuesday morning.

That's how things turned out, with subzero overnight temperatures in four states plus the ACT, where Canberra dipped below zero to -0.3°C just before 7 am, the capital's first subzero night since September.

• For those who love stats, Canberra's record October low since data started being collected in 1939 was -3.3°C way back in 1957.
• Only in the three summer months of Dec, Jan, and Feb has Canberra never dipped below zero overnight.
• Canberra's minimum was the lowest in October for six years, while Sydney's low of 9.8°C was mild by comparison but still the lowest for seven years in October.

Here's a rundown of the coldest overnight temps in all eight states and territories in the 24 hours to 9 am this Tuesday, October 17.

(Please note that weve compiled this info before 9 am in some Australian time zones and will update if there are any changes.)

• NSW: Thredbo Top Station -4.5°C
• TAS: Liawenee -3.8°C
• VIC: Mt Buller -3.7°C
• ACT: Mt Ginini -2.7°C
• SA: Keith West -1.5°C
• WA: Wandering 5.5°C
• QLD: Applethorpe 5.5°C
• NT: Alice Springs Airport 8.8°C

The blue belt on the map below shows the coldest part of the country overnight.

Note that even some areas away from the ranges and tablelands of eastern Australia had cold nights by October standards.

• For example, Mount Hope a tiny map speck in the Lower Western forecast district of NSW, dipped to -1.1°C.
• Mount Hope started October with a day of 37 degrees, so a 38-degree gap between the coldest and hottest temps within a month is a significant difference.
• It was also the coldest October night for 10 years in the NSW Riverina town of Narrandera (1.2°C) and the coldest in 12 years in October in the Tasmanian town of Sheffield (0°C).

The cold front that ushered in this unseasonably chilly airmass has now moved out into the Tasman Sea, but cool air in its wake will continue to deliver cold temps for the next night or two in the southeast, as a high pressure system centred over eastern Australia keeps conditions calm overnight in most areas.