On 18 February 2017, severe thunderstorms affected much of northern Sydney. From around 4.00pm, large hail affected a number of suburbs; ranging from four-centimetre hail recorded in Hornsby, Thornleigh and Pymble up to nine-centimetre hail in Annangrove.
The New South Wales State Emergency Service received over 2,700 requests for assistance in relation to damage from the storm, while still managing the workload from storms in the greater Sydney area the previous day. Over 1,000 of these requests were concentrated in northern Sydney, the area worst-affected by the large hail.
Three people were injured when they were struck by lightning near Bowral, south of Sydney.
Insured losses from this event were substantial. Over 50,000 insurance claims were received with estimated losses exceeding $328 million.