When a call lightning spell is cast, there must be a storm of some sort in the area—a rain shower, clouds and wind, hot and cloudy conditions, or even a tornado (including a whirlwind formed by a djinn or air elemental of 7 Hit Dice or more). The caster is then able to call down bolts of lightning. The caster can call down one bolt per turn. The caster need not call a bolt of lightning immediately—other actions, even spellcasting, can be performed; however, the caster must remain stationary and concentrate for a full round each time a bolt is called. The spell has a duration of one turn per caster level. Each bolt causes 2d8 points of electrical damage, plus an additional 1d8 points for each of the caster's experience levels. Thus, a 4th-level caster calls down a 6d8 bolt (2d8+4d8).
The bolt of lightning flashes down in a vertical stroke at whatever distance the spellcaster decides, up to 360 yards away. Any creature within a 10-foot radius of the path or the point where the lightning strikes suffers full damage unless a successful saving throw vs. spell is rolled, in which case only one-half damage is taken.
Because it requires a storm overhead, this spell can only be used outdoors. It does not function under ground or under water.