The frequency of Australian thunderstorms varies from as few as 5 per annum in the south east of Tasmania, to over 90 per annum around Darwin in the Northern Territory.
Thunderstorms are most common in the warmer months, almost exclusively so in the tropical north.
In late Spring - Summer a combination heat convection, lowering air pressures and rising moisture levels trigger large areas of thunderstorms over northern Australia. These air masses and low pressure systems on a broader scale are one of the factors that drive the North West Monsoon of Northern Australia. Later in Summer monsoonal cloud masses themselves commonly contain numerous embedded thunderstorms. These storms are usually very small and brief. Small hail is common in these storms.