A winter deluge that is set to smash Perth's June rainfall average will coincide with the shortest day of the year to deliver a wet, gloomy and blustery weekend for the city.

Key points: The winter solstice on Saturday will coincide with heavy rain for Perth

The winter solstice on Saturday will coincide with heavy rain for Perth It comes on the back of a series of storms that hit earlier this month

It comes on the back of a series of storms that hit earlier this month The rain is welcome in agricultural areas after a dry start to 2019

A cold front sweeping up from the southern ocean will drag moist tropical air from the north-west over much of Western Australia from Friday evening, the night of the winter solstice, and into Saturday and Sunday.

Perth could get more than 50 millimetres of rain over the weekend.

"It does look as if we're going to see another big cloud band moving down from the north-west and a cold front in association with that, similar in nature to the major rain event that we had earlier this month," Bureau of Meteorology (BOM) spokesman Neil Bennett said.

"[It's] almost a repeat performance of what we had a week or so ago.

"And like that previous event, it's expected to bring widespread rain across much of the agricultural districts and again it's looking likely that there'll be some good falls."

Rain brings good news for farmers

After the early winter drenching, Perth has recorded 118.6mm of rain since the start of the month, almost reaching its June average of 124.5mm.

This rainfall event is likely to see the city far exceed its average, but should also deliver double digit totals to inland areas.

The system is set to bring heavy rain to Perth and south-west WA this weekend. ( Supplied: RAMMB )

"West Coast areas are likely to be where the heaviest falls are, but the rain is going to get right across during the course of the weekend, so we'll be getting into the whole of the agricultural area," Mr Bennett said.

"But there will be areas that will miss out of the really heavy stuff."

As the rain is coming from a north-westerly direction, some areas of the south coast may miss out on the heavier falls.

"When you get the northerly winds, you get a bit of a rain shadow effect on the southern side of the Porongurup Ranges and the Stirlings, which is why they don't get quite so much rainfall compared to the Katanning, Busselton, Bridgetown areas where there's heavier falls …" Mr Bennett said.

"But if they get an embedded thunderstorm in amongst it, then things change dramatically."

Storms, squally winds, large swells on the cards

The system could also see wild weather hit the state, with forecasters keeping a close eye on the likelihood of severe storms developing.

"There's a possibility now that within the cloud band we could see some embedded thunderstorm activity, especially as the leading edge gets in towards us and there may be some squally winds associated with that," Mr Bennett said.

"The bureau will be looking at the situation over the next day or two to determine whether a severe weather warning will be warranted.

"We're also going to have to take a look very closely at the swells, so obviously with the recent beach erosion, that's something that could be a problem as well."

The Port Beach coastline has been hammered by recent storms, leaving buildings in danger. ( Supplied: City of Fremantle )

Perth forecast