Flash flooding

What is flash flooding?

Flash flooding happens when too much rain falls too fast for too long, and the ground doesn’t absorb all the water. 

Flash flooding can be within a few minutes, but usually within a few hours and can happen away from where the rain fell. 

There may be little to no warning time and the quick rise and possible depths of flash flooding makes them very dangerous. 

Flash floods happen in regional, rural, remote and urban areas. In urban areas, places where rainfall cannot be absorbed create possible flash flood locations, with runoff draining to lower-lying areas. 

Flash flooding can also happen around bridges, drains, culverts, creeks and causeways.

During flash flooding

During flash flooding, you may need to rely on yourself, family, friends or neighbours. NSW SES may not be able to get to you immediately or it may be too dangerous to rescue you.

Knowing your flash flood risk will help you plan, prepare, respond and recover better.

When flash flooding is likely the best action to take is to leave low-lying areas (evacuation) well before flooding begins, but only if it is safe to do so.

Know your risk

• If you live or work close to a river, water course, creek, drain, culvert or in a low-lying area, you may be at higher risk from flash floods even if you have never experienced them before.
• Flash floods can be several metres deep, rise quickly and move fast.
• Talk with neighbours, community members, local groups and organisations about the local flash flood risks.
• Know when your property and local roads are affected by flash floods. Identify the key triggers and actions you need to do, including safe roads to take if you need to leave.

Know the warnings

• Monitor the Bureau of Meteorology website for Severe Weather and Severe Thunderstorm Warnings.
• You may not always receive an official warning for flash floods. The natural signs can include rushing or pooling water and heavy and prolonged rainfall.

Act early

• When flash flooding is likely the best action to take is to leave low-lying homes and businesses (evacuation) well before flooding begins, but only if it is safe to do so.
• Bring children indoors during severe weather to avoid drains, culverts or creeks as rushing and pooling water can make these dangerous places.

Make safe decisions

Stay safe

After flash floods, ensure the structural stability of your property before entering. Check for damage to windows, walls and the roof and be especially cautious of potential poisons, including asbestos.

Look out for each other

• Get to know your neighbours. Helping each other before, during and after disasters will help communities prepare, respond and recover better.
• Share flash flood risk information with your family, friends and neighbours.
• Support someone who may require further assistance.

Additional resources