Thunderstorms during the months of June and July are rare events due to the lack of essential ingredients such as heat and adequate moisture available.
On Sunday afternoon, a rare mid June thunderstorm developed over Western Sydney which then tracked east towards the coast.
The last time I remember seeing a thunderstorm occur in June was early June 2017. This event has broken a thunderstorm drought for the month.
While non sever, it did feature numerous thunderclaps and at the time of taking the photos at Doonside, two strong cloud to ground lightning strikes were observed.
No hail was observed but the raindrops were large and sustained for the duration. The raindrops were cold suggesting that hailfall was possible.
Rainfall varied between 1 and 5 mm across Blacktown depending on location.