News

Summer heat taking a break in southeastern Australia

Cool and dry air replaced heat and humidity across southeastern Australia on the weekend, bringing some welcome relief from an unusually uncomfortable summer.

After a prolonged period of heat and humidity caused by a blocking high pressure system in the Tasman Sea, a strong cold front associated with a polar airmass finally swept across southeastern Australia last weekend.

The video below show a dry airmass (oranges and reds) behind this front replacing the muggy air (blues and purples) ahead of it on the weekend.

Video: Dewpoint forecast from Thursday, February 13 to Sunday, February 16, according to ECMWF

This cooler and drier air mass spread over Sydney towards the end of last week, causing the city's dew point temperature to drop from 22°C on Friday afternoon to about 6°C on Sunday afternoon.

The dewpoint is the temperature at which air must be cooled to achieve a relative humidity of 100%, or saturation. Higher dew point temperatures mean there is more moistre in the air, which makes it harder for people to lose heat through the evaporation of sweat from their skin. By contrast, lower dew points can enhance evaporation, which usually makes the air feel cooler.

Image: A rough guide to how different dew point temperatures would make people in Australia’s sub-tropical climate feel.

The whole of southeastern Australia experienced an unseasonable chill in recent days as a cool and dry air mass spread across the region.

Melbourne shivered through its coldest morning this early in the year for 37 years, when the mercury dropped to 9.9°C on Sunday morning.

Monday morning was Sydney's coolest February temperature in 12 years, with the city’s temperature dropping to 14.5°C

Canberra dipped to 3.1°C on Sunday morning and 4.2°C on Monday morning – the first time the mercury had plummeted to single digits this February

Cooler than average conditions will continue across much of southeastern Australia until later this week, when a heat starts to rebuild ahead of another cold front.