Canberra could be inundated with rain and hail Thursday evening with a thunderstorm expected to hit the territory.
The Bureau of Meteorology issued a severe thunderstorm warning for the ACT at 6pm, with potential flash flooding and large hailstones on the way.
Forecaster Rebecca Kamipakahara said thunderstorms were developing north-west and south-west of Canberra.
"Our concern with these storms is primarily rainfall as they're fairly slow-moving in a fairly moist atmosphere,' she said.
"Large hail is also possible due to the size of the thunderstorm [and could] reach Canberra. Some of these thunderstorms are reaching up to 10 to 12 kilometres vertically in the atmosphere. When you get thunderstorms that large, it's highly possible to see some larger hail stones come out of them."
Storms and showers are set to continue throughout the week.
Ms Kamipakahara expected similar weather conditions on Wednesday, with a forecast top of 29 degrees.
"We're expecting a chance of thunderstorms probably in the afternoon or evening," she said.
"On Thursday and Friday, the low-pressure trough that's causing all these thunderstorms right across NSW, that might track a bit further west so, the chance of thunderstorms will contract west of the ACT towards the end of the week."
In the meantime the SES is advising residents in Canberra and Queanbeyan to move cars under cover and away from trees; secure items outside the home; keep clear of fallen power lines, waterways and drains; unplug appliances; and avoid using phones during any storms.
For emergency help in floods and storms, phone the SES (NSW and ACT) on 132 500.