Right on cue for the start of winter, a series of cold fronts will deliver a week of consistent showery weather for Perth and southwest WA, with light showers already scooting through the region on Wednesday morning and heavier rain likely to commence this afternoon or evening.

While much of eastern Australia has been unseasonably wet and mild this week as a complex series of troughs and upper and lower level low pressure systems interacts with a tropical moisture feed, the southwest can expect a classic winter pattern with repeated cold fronts.

Statistically, the coming rain is overdue

May is typically Perth’s fourth-wettest month, with an average rainfall of 85.5mm. To 9am this Wednesday, May 27, the WA capital has had a relatively dry month, with only two rain days and a total of just 11.8mm recorded in the city.

Clear skies tend to bring cool nights, which is why Perth’s running average minimum for May 2026 is around two degrees down on average. That includes Perth’s lowest May temperature in seven years on Sunday morning, when the mercury fell to 2.5°C.

How much rain is likely in the next seven days?

The 7-day predicted rainfall chart (below) reveals a purple zone around Perth, indicating 100mm or more in total. That would be around the upper limit of accumulated rainfall associated with the coming systems. 

Image: Predicted accumulated rainfall totals for southwest WA for the seven days to Tuesday, June 2, 2026, according to the ECMWF model. Source: Weatherzone.

But it appears likely that Perth could see falls in the vicinity of 10 to 20mm later this Wednesday with a similar range expected on both days this coming weekend. Lighter totals are expected on Thursday, Friday, and early next week.

Thunderstorms are also a possibility in the southwest this evening, which would obviously cause some heavier rainfall totals over a relatively short duration at some locations.

Will it get significantly cooler?

The first front doesn’t have a particularly strong bite to it in terms of air temperatures, but the weekend system will definitely drop daytime temperatures by a few degrees, especially in the new week.

Perth is expecting maximums a degree or two below the May average of 22.5°C from Thursday through to the end of the month on Sunday, then maximums of 18°C next Monday and Tuesday (June average 19.5°C).

But the main story is the wet weather, which is always welcomed by most locals at this time of year. 

In 2025, Perth exceeded its average monthly rainfall in June, July, August and September – the first time that had happened in all four months for 18 years. There won’t be too many arguments if it’s similarly wet this winter.