@nique,
When K-Index is too high (3 and above) there is a good probability that the drone flying and using GPS data will be affected by solar storm activity. Solar flares can interfering with satellites including GPS satellites and their signals being beamed to earth. There is a reasonable expectation that high solar activity will cause your GPS receiver to loose it’s fix and can cause fly-aways. If you fly in manual mode ie., stabilized or any flight mode not using GPS information, you have nothing to worry about. As for compass interference, I’m not sure how much of the earth’s magnetic fields will cause compass errors.