Magnetic storm
A magnetic storm was both a planetary and a spatial phenomenon that posed a navigational hazard in the early days of space travel. At that time, the impulse engines were not ful enough to resist the effects of such storms, and a starship encountering one could be swept off course.

In space 
Around 2065, an encounter with a magnetic storm swept the  into the galactic barrier, initiating a series of events that led to her destruction. ()

In 2267, the  encountered a magnetic storm at the Halkan homeworld, while James T. Kirk and his landing party were on the surface conducting negotiations. The storm was reported by Spock to be a "standard ion type, but quite violent and unpredictable." During the beam up to the ship, interference by transporting through a magnetic storm caused the crew to transport to an alternate mirror universe. ()

In 2268, the Providers wanted to make the crew of the Enterprise thralls on Triskelion, destroy the ship, and let its destruction appear as being caused by a magnetic storm. ()

Spock mentioned that no magnetic storm was located in the sector to exclude this as a possible reason for the heavy interference in communication with Starbase 6. ()

In 2353, the Kohl settlement was hit by a solar flare. Magnetic storms and extreme levels of radiation followed. ()

In 2373, the shuttlecraft Sacajawea crashed due to a magnetic storm, while attempting to collect nitrogenase compound. Captain Kathryn Janeway was severely injured. ()

On planetary surfaces 
Magnetic storms could also occur on the surface of some planets. On Rigel XII, they were accompanied by or cause extremely powerful sandstorms. Such a storm nearly claimed the life of Eve McHuron in 2266; only lithium miner Ben Childress' determined search located her. ()

While attempting to extract their away team from Augris' species planet in 2372, the  hid within a large magnetic storm over the planet's northern magnetic pole to avoid the phased ion cannons of the Mokra Order. ()

See also 
 Electromagnetic storm

de:Magnetsturm
Meteorology
Astronomical phenomena