Perth has experienced its second warmest January to June period on record with the average daily maximum temperature for the past six months reaching 27.4C.

Bureau of Meteorology climate information officer John Relf said the average maximum temperature for this period was 26.4°C, with the highest on record occurring in 1978 with a 27.6C average.

Mr Relf said Perth had near average rainfall in June, with 156.2mm of rain falling over 19 days.

Historically, the average June rainfall was 177mm across 15 days.

Perth experienced its wettest June day on Sunday where 23.2mm of rain fell.

Water is starting to flow in Perth's dams with Mundaring Dam at 40 per cent capacity at 25.5GL and the Serpentine Main Dam at 35.9 per cent of capacity at 49.4GL.

Earlier this week, Water Corporation spokeswoman Clare Lugar said Perth was about one month behind its usual dam levels for this time of year.

"It's just been so dry. The ground is like a sponge so we need that long, persistent rain before the water can flow out into the streams and into the dams," she said.

Perth is now one third of its way into winter and Mr Relf said July was typically the coldest and wettest winter month.

"Many days are cloudy, wet and windy, though there are generally some sunny days with light winds and cold nights," he said.

"On average, Perth can expect six days when the maximum temperature is 20C or more.

"The greatest number of such days in July was 14 days in 1976 and 1977. Last July, Perth recorded four such days."

Mr Relf said records showed on average Perth residents could expect two July days where the maximum temperature is 15C or below.

In July 2008, Perth had just two days of maximum temperatures less than 15C.

In 1916, Perth shivered through 12 July days of temperatures less than 15C.

Cold nights were also likely this month, with records showing Perth has at least eight July nights with minimum temperatures falling to 5C or less.

Mr Relf said after showers cleared this afternoon, fine days were ahead with maximum temperatures of 20C and 21C forecast for Saturday and Sunday respectively.

Wintery conditions are set to return on Monday with the forecast of showers.

PERTH LISA CALAUTTI