West Aussies have been stuck in two weather extremes this week, enjoying unusually dry and sunny days but feeling the sting overnight as temperatures took a tumble.

Weather experts at the Bureau of Meteorology have revealed that an unusually intense high pressure system sitting over large parts of Western Australia is behind the unusual pattern.

“When we see high pressure like this it means air doesn’t rise and doesn’t create cloud or rain, so the weather is more settled – that’s why it’s been relatively dry and sunny this week,” senior meteorologist Ilana Cherny explained.

“When we see a recording of around 1040 hectopascals (hPa), that’s when we consider the air pressure to be very high”.

On Friday morning, BOM recorded 1039hPa in Esperance and 1036hPa in Perth.

“Generally when we have clear and settled conditions, it allows for surface temperatures to drop overnight,” Ms Cherny said.

“Coupled with a strong cold front that has been sweeping over the region, this has caused the cold mornings we’ve been seeing.”

The mercury dropped to 5.1C in the Perth metro area overnight Thursday, with Perth Airport recording a slightly higher temperature of 6.7C.

North of Perth in Gingin, temperatures dropped to just 3.2C.

The meteorologist continued: “It’s the coldest it’s been in the Perth area for the last couple of weeks, with the last three days recording less than six degrees overnight, which is below the average minimum temperature for this time of year. Usually the average is about 8 degrees”.

Elsewhere in WA, temperatures dropped well below zero degrees in places in the Goldfields-Esperance region Thursday night, with Salmon Gums recording -4.4C and Norseman -1.8C.

“When we see these kinds of temperatures that’s when frost develops and that has an impact on agricultural practices, with farmers being unable to crop,” the weather expert explained.

The high pressure system has also impacted the volume of rainfall the region has seen in the last week.

“It has been unusually dry in the south of Western Australia. Winds go anti-clockwise in the southern hemisphere and where they’ve been travelling around a high pressure system, it’s bringing very dry air that’s travelled over the continent to the state”.