The variable conditions in interplanetary space, usually caused by solar disturbances, which affect human health or technological systems such as satellite navigation (Global Positioning System), radio communications, and spacecraft electronics. Major geomagnetic storms caused by fast-moving streams of solar wind from coronal holes and coronal mass ejections (CMEs) are the principal space weather events. Other effects are caused by X-rays, radio bursts, and energetic particles generated by solar flares and CMEs. Examples of space weather damage include the effects of energetic electrons or ionized atoms penetrating spacecraft electronics or a human body, ionospheric disturbances that affect radio propagation, and electrical currents induced in the electrical grid or pipelines on Earth.

http://swe.ssa.esa.int/what-is-space-weather Space weather information at ESA.

http://www.swpc.noaa.gov/ Space Weather Prediction Center.