Cumulonimbus clouds, also known as thunderclouds, are the tallest of all cloud types. They can reach incredible heights, typically between 5,000 and 13,000 meters (16,000 to 43,000 feet), with some towering even higher.

Here's a breakdown:

* Average Height: 5,000 to 13,000 meters (16,000 to 43,000 feet)

* Maximum Height: Some cumulonimbus clouds can extend even higher, reaching up to 20,000 meters (65,000 feet) or even higher.

Important Note: The height of a cumulonimbus cloud can vary greatly depending on factors like atmospheric conditions, temperature, and humidity.