Catatumbo lightning is an atmospheric phenomenon that occurs over the mouth of the Catatumbo River where it empties into Lake Maracaibo in Venezuela. It originates from a mass of storm clouds at an altitude of more than 1 km, and occurs during 140 to 160 nights a year, 10 hours per day, and up to 280 times per hour. It occurs over and around Lake Maracaibo, typically over a bog area formed where the Catatumbo River flows into the lake. The lightning changes its frequency throughout the year, and it is different from year to year. For example, it ceased from January to March 2010, apparently due to drought, leading to speculation that it might have been extinguished permanently.
Catatumbo lightning usually develops between 8°30′N 71°0′W and 9°45′N 73°0′W. The storms are thought to be the result of winds blowing across Lake Maracaibo and the surrounding swampy plains. These air masses meet the high mountain ridges of the Andes, the Perijá Mountains (3,750 m), and Mérida’s Cordillera, enclosing the plain from three sides. The heat and moisture collected across the plains create electrical charges and, as the air masses are destabilized by the mountain ridges, result in thunderstorm activity. The phenomenon is characterized by almost continuous lightning, mostly within the clouds. The lightning produces a great quantity of ozone though its instability makes it unlikely that it has any effect on the ozonosphere.