Parts of Western Australia had its warmest August day in decades. The mercury skyrocketed at Swanbourne, hitting 26 degrees by lunchtime. Shortly after lunch, it hit 28 degrees, making it the warmest August day in 17 years. Jandakot equalled its warmest August day in 24 years of records, hitting 27 degrees, equal to the record set in 1998. For Perth City it was the warmest day since April, reaching 27 degrees. Collie had it warmest August day in over a decade, reaching 24 degrees. At Rottnest Island, it was the hottest August day in 29 years of records as the mercury crept up towards 25 degrees. Garden Island recorded 25 degrees, which makes it the warmest August day in 14 years of records. Temperatures soared to over seven degrees above average for Geraldton in the Central West, Collie in the Southwest and Meekatharra in the Gascoyne. Tomorrow a low pressure trough and embedded low will begin move closer to the coast, bringing slightly cooler temperatures, with the rain arriving during Monday.