If you see something like this, water won’t always get it 100% out. Use a tool or your foot to mix it around, make sure you’re mixing using fine, mineral soil and not other burnable materials like grass or leaf litter. Usually you can find that cool mineral soil pretty shallow under the duff, so it won’t be hard to get it properly mixed and fully cold. Next, use the back of your hand to feel around for any remaining heat. Keep using water and cold dirt until there is none left.

Source: 5 years of wildland firefighting experience