A Force Storm as seen on Nam Chorios (Legends).
The Force storm was a Force power that seemingly brought together the elements of Force Whirlwind and Force lightning, resulting in an effect similar to a dry tropical storm. The most effective use was likely in a concentrated manner within a limited area.
This ability, also referred to as "Summon Storm," used telekinesis to manipulate the atmosphere, causing the weather to violently swirl around the user. A proficient practitioner could generate storm conditions across areas spanning several kilometers, with durations reaching multiple hours.
The storm involved sheets of rain that hampered sight and saturated everything, along with powerful winds that tossed around loose items and whipped at plant life. The presence of random lightning strikes made the storm dangerous enough to ground aircraft and significantly disrupt any activities, including combat.
It is clear that this ability could only be deployed in open-air environments, and its effectiveness was subject to the existing climate. While one could not manifest a rainstorm within a desert, the creation of a hazardous sandstorm was certainly plausible.
Although not intrinsically a dark side power, it was more frequently employed by individuals aligned with the dark side, such as the Sith and the Nightsisters hailing from Dathomir, due to its widespread and indiscriminate destructive potential.
Some iterations of this power resulted in less damage compared to Force lightning.
During the reconquest of Yuuzhan'tar, Luke Skywalker manifested a Force storm around himself as he surrendered himself to the Force while engaged in combat.