A trough of low pressure developed over Victoria on 23 December, deepening further on 25 December, before progressing east on 26 December with a cold frontal push. On 25 December, thousands of homes were damaged when thunderstorms swept across Melbourne, bringing flash flooding and hail.

The State Emergency Service received more than 4200 requests for assistance, most resulting from hail damage, wind damage and flash flooding through the western and northern suburbs of Melbourne. Severe thunderstorms first developed to the west of Melbourne, south-east of Ballan, at approximately 2.30 pm on Christmas Day. During the next seven hours up to five long-lived supercells (very severe long lasting thunderstorm cells) moved eastwards across the northern suburbs of Melbourne.

The northern Melbourne suburbs of Eltham, Broadmeadows and Keilor were among the worst hit. There were reports of two tornadoes in Fiskville and Melton with some carsbeing upended. More than 50 volunteers arrived from interstate to help repair damaged homes. The State Government paid 220 emergency relief payments. An information centre was established in Keilor Downs to help residents who experienced storm damage. Representatives from the SES, Department of Human Services, Red Cross and the Salvation Army provided assistance to help residents who experienced storm damage.

The Insurance Council of Australia declared the weather event as a catastrophe. It received up to 30,000 claims for damage to houses, businesses and motor vehicles. The Insurance Council of Australia estimated the preliminary 2017 damage at $987.9 million.