News

Heaviest May rainfall in 82 years recorded in WA town

Parched areas of southwest WA have finally seen some rain this week, with Wandering recording its highest May rainfall in more than 82 years and the most rainfall the town has seen in 13 months.  

The rain event began on Wednesday, with Bunbury recording a 2-day total of 55 mm to 9am on Friday, May 3, which is the most rain the town has seen since August 2023 and a 3 year high for May. Cowaramup also saw their largest rainfall totals in two and a half years, with 60 mm recorded during the 24 hours to 9am on Thursday, May 2. 

The rainfall intensified on Thursday as severe thunderstorms and a cold front swept across the region, with some towns recording more than 100 mm of rain in a day in the southwest of the state. 

Image: 24-hour rainfall to 9am on Friday, May 3. Source: Bureau of Meteorology 

The largest falls in the 24 hours leading up to 9am on Friday, May 3 were; 

• Brookdale Siding, which saw 120mm 
• Wandering recorded 45.6mm, its wettest May day in more than 24 years, and the most rainfall the site has seen in 13 months. This rainfall is just under a month’s worth of rain. 
• Dwellingup saw 39.4mm 
• Collie East recorded 38mm, a quarter of its monthly average 
• Bunbury observed 35.6mm, its highest May rainfall in three years 
• Karnet hasn’t seen rainfall like this since July 2022, with 35mm falling in the guage. 

Much of this rain fell in a matter of hours as severe thunderstorms lashed the southwest of the state. The areas that saw the most intense rainfall on Thursday, May 2 were: 

• Brookdale Siding saw 66 mm in the 3 hours to 5:45pm, which has only a 1% chance of occurring in any given year 
• Bunbury recorded more rainfall in an hour than it has in the last 7 months, with 17.6mm falling in the hour leading up to 11am. During the 7 months before May 2024, the site has seen only 15.8mm.  
• Mount William recorded 45.4 mm in the 1 hour to 1:05pm. 

The video below shows a waterspout off the Mandurah coast in WA on Thursday, May 2. 

 Video: Waterspout and storm clouds off Mandurah coast WA on Thursday, May 2. Credit: tomproudfoot 

The rainfall that has fallen over the past two days has been very welcome for those in the southwest suffering from the driest 7-month period on record.  

Image: Rainfall anomalies between 1 October 2023 to 30 April 2024, source Bureau of Meteorology.  

While this rainfall was not drought-breaking, it has been a great start to May and will go a long way to reducing these rainfall deficiencies in some areas.