A fire storm was a type of weather pattern.
Bersallis III was a planet subject to violent fire storms every seven years. They would form when solar flare radiation from the planet's sun reacted with high energy plasma that was present in the planet's atmosphere. In 2369, an unusually large and fast-moving fire storm overwhelmed the colony's defenses established for that purpose. The USS Enterprise-D was dispatched to the planet to evacuate the colonists before the fire storm destroyed the colony. Lieutenant Commander Nella Daren led several away teams to the surface to establish a barrier using thermal deflector units, a technique she was familiar with through previous experience. The mission was ultimately successful and the 643 colonists were evacuated but eight members of the away team were lost. (TNG: "Lessons")