Lightning is a giant discharge of electricity accompanied by a brilliant flash of light and a loud crack of thunder.
Lightning is the result of the difference in electrical charge between the top and bottom of a cloud.
Lightning is not confined to thunderstorms. It's been seen in volcanic eruptions, extremely intense forest fires, surface nuclear detonations, heavy snowstorms, and in large hurricanes.
Lightening is mainly associated with the convective clouds. Monsoon clouds are mainly stratiform. Therefore, lightning generally does not occur during the active phase of the monsoon season.
However, the convective activity during the break spell of the monsoon may lead to formation of convective clouds and hence the lightning.