Towering cumulus clouds can be based in the low or middle height ranges and achieve considerable vertical development (family D2) in areas of deep, moist convection. They are an intermediate stage between cumulus mediocris and cumulonimbus. There are several subtypes of this kind of cloud.

For specific information on this type of cloud, see:

Cumulus congestus clouds (also towering cumulus) are characteristic of unstable areas of the atmosphere which are undergoing convection. They are often characterized by sharp outlines and great vertical development. Because cumulus congestus is produced by strong updrafts, it is typically taller than it is wide, and cloud tops can reach 6 kilometres (20,000 ft), or higher in the tropics. Cumulus congestus clouds are formed by the development of cumulus mediocris generally, though they can also be formed from altocumulus castellanus or stratocumulus castellanus as well. The congestus species of cloud can only be found in the genus cumulus.

Cumulus congestus will mature into cumulonimbus calvus under conditions of sufficient instability. This transformation can be seen by the presence of smooth, fibrous, or striated aspects assumed by the cloud's upper part. This cloud type produces precipitation, often in abundance.