Amazing Outback: When do you know that it will rain soonish

The outback is very flat and any rain (even short ones) can build up water really quickly. For ants that could become potential deadly when the water runs into their ant nest. So when rain is on the horizon ants build walls around the entries to their nest to protect them from the flowing water.

So if you see those walls around their entries the chances are pretty high that it might rain very soonish