Several towns across the south of WA awoke to sub-zero temperatures this morning.
The lack of overnight cloud cover made for a frosty morning, with temperatures dropping as low as -2C in Southern Cross, 370km east of Perth.
In Wandering, 120km south-east of Perth, the mercury reached -0.8C before sunrise and stayed in the negative after dawn.
Kalgoorlie-Boulder reached an overnight minimum of 1.2C at 6.20am.
By 7.10am, the temperature at Perth Airport was 1.3C, compared to 2.1C in Mt Lawley, 0.3C in Gingin and 1.5C in Bridgetown.
A Bureau of Meteorology spokesman said cloudless winter nights made for cold mornings.
"The earth radiates heat during the evening," he said.
"When there's cloud, the cloud actually reflects the heat so it doesn't escape the atmosphere.
"Without cloud, it gets cooler a lot quicker."
Forecast minimums for Perth are 3C tomorrow and 2C on Wednesday morning, before cloud cover provides some early-morning relief.
Temperatures are expected to hover in the high-teens over the weekend.