Three key ingredients are needed for thunderstorm formation; namely heat, moisture and instability, all of which will be present around the country today.

Firstly, hot air building across inland Australia is being drawn towards the nation's extremities by a number of low pressure troughs.

These troughs, which are strewn across the country's west, south and east, are also dragging moisture in from the surrounding oceans, dampening the atmosphere.

The final ingredient, instability, is present as the humid air from the oceans clashes with hot air from the interior, allowing the less dense warm air to rise. This battle of the airmasses generally occurs along the low pressure troughs, where thunderstorms then become most active.

Over the next 48 hours, the main areas of severe thunderstorm activity will be over southeastern and southwestern Australia.

Storms in the southeast, affecting New South Wales, Victoria, Tasmania and South Australia, will be slow moving and pose a risk of flash flooding from heavy downpours.