A Thunderwyrm is one of the most horrible Wyrm beasts a Garou can fear to meet in combat. Massive monstrosities in their own right - the biggest ever encountered spanned around the size of two football fileds and contained a Wyrm Caern within her guts- , they resemble pale earthworms with enormous jaws filled with jagged teeth. Usually, they sleep beneath the surface or travel underground, literally eating their way through the earth. They are only drawn to the surface during storms, but when they erupt from the earth, they are capable of massive destruction and vanish afterwards without leaving a trace. Their periods underground are usually spent breaking down the things they devoured during their attacks on the surface and to accelerate their size.
Some Uktena claim that the first Thunderwyrm was born from radioactive soil.