This morning, southeast Australia recorded its lowest October minimum temperatures in decades, with minimum temperatures dropping as much as 10 degrees below the October average in some places.

Image: Observed temperatures over the southeast at 5:15am EDT Saturday 26th October.

The chill was driven by a broad high-pressure system directing an exceptionally dry air mass from subpolar and near-polar latitudes into southeast Australia, combined with clear overnight skies and widespread light winds. The images below present dew points at two levels in the lower atmosphere—approximately 1.5 and 3 km above the surface—indicating a very dry air mass, with dew points below 0°C. Areas shown in lilac and white indicate extremely dry conditions, with dew points dropping below a whopping -30°C.

Images: Dew points and winds at 850 hPa (about 1.5 km above the surface, top) and 700 hPa (about 3km above the surface, bottom) and mean sea level pressure according to the GFS model.

This setup caused minimum temperatures to plunge to between -7°C and -8°C in parts of the Snowy Mountains, particularly around Perisher Valley and Cooma Airport. Canberra also recorded a minimum below freezing, marking its coldest October morning in a decade. 

Here's a summary of today’s standout minimum temperatures: 

NSW 

- Perisher Valley: -7.7°C (coldest October minimum since last year, nearly 9°C below average); 

- Cooma Airport: -7.1°C (coldest October minimum in 11 years, about 10°C below average); 

- Bombala: -4.6°C (coldest October minimum in 18 years, about 9°C below average); 

- Goulburn Airport: -2.9°C (coldest October minimum since last year, 8°C below average); 

- Nerriga: -2.5°C (coldest October minimum in over 11 years, 10°C below average); 

- Canberra: -1.3°C (coldest October minimum in 10 years, nearly 8°C below average); 

- Nowra: 3.6°C (coldest October minimum in 16 years, 7°C below average); 

- Moruya Airport: 1.9°C (coldest October minimum in 11 years, nearly 8°C below average). 

VIC 

- Mount Hotham: -5.6°C (coldest October minimum, about 6°C below average); 

- Mount Hotham Airport: -4.6°C (coldest October minimum, about 7°C below average); 

- Falls Creek: -4.5°C (coldest October minimum, about 6°C below average); 

- Omeo: -2.8°C (coldest October minimum in 12 years, nearly 8°C below average); 

- Mount Buller: -2.8°C (coldest October minimum, about 4°C below average); 

- Westmere: -1.8°C (coldest October minimum, about 7°C below average); 

- Tatura: 0.5°C (coldest October minimum in 7 years, 7°C below average); 

- Melbourne Airport: 1.7°C (coldest October minimum); 

- Melbourne Olympic Park: 5.9°C (coldest October minimum, nearly 4°C below average). 

TAS 

- Liawenee: -5.1°C (coldest October minimum, about 6°C below average); 

- Kunanyi/Mount Wellington: -3.6°C (coldest October minimum, about 4°C below average); 

- Bull Bay Lauriston: -2.8°C (coldest October minimum, about 10°C below average); 

- Tunnack: -2.6°C (coldest October minimum, about 7°C below average).