Perth is on track to breaking another weather record as low daytime temperatures continue this week.

Weatherzone meteorologist Robert Wood said widespread cloud cover was contributing to the "massive reduction" in day-time temperatures experienced across WA so far this month.

Perth is set to record its second day in a row where the mercury won't reach 14 degrees, which hasn't occurred for 13 years.

Despite the low maximums, Perth's overnight temperatures remained around 10 degrees for the past two nights, and today's highest temperature – 11.6 degrees at 12.30pm – is just 1.3 degrees higher than the overnight low recorded at 5.30am.

So far this month, Perth has had five consecutive days where the overnight temperatures dropped below five degrees, and on every day except one, the maximum had not exceeded 17 degrees.

Yesterday, the Gascoyne Junction recorded its coldest day in 45 years, with the temperature climbing to a chilly 13 degrees.

Jurien Bay also had its coldest July day in 39 years, reaching just 13 degrees yesterday.

Mr Wood said that in addition to a chilly Sunday, Gascoyne Junction also had some heavy rainfall over the weekend.

"The Gascoyne district was the focus of the heaviest falls in the 24 hours to 9am on Sunday," he said.

"Carnarvon picked up 3o millimetres through this period, while further inland, Milly Milly had 50mm."

Rainfall was not quite as heavy in the 24 hours to 9am today, although Morawa and Dalwallinu each recording more than 20 millimetres.

Mr Wood said cloudy and wet conditions had now taken hold of WA, bringing a burst of useful rainfall in addition to the record cold conditions.

"An upper level low formed to the west of Geraldton in the last 48 hours, drawing on abundant moisture from over the Indian Ocean, is leading to widespread cloud cover, rainfall and chilly day-time temperatures across WA," Mr Wood said.

Follow WAtoday on Twitter @WAtoday