By concentrating (no movement allowed), the caster causes one of the following conditions to manifest around him or her. This spell only functions outdoors.
Calm: Clears bad weather (though side-effects-e.g. mud after rain-remain.)
Extreme heat: Dries up snow or mud (including transmute rock to mud). Creatures in the area move at half normal rate.
Foggy: Visibility drops to 20'. Creatures in the fog move at half their normal rate. At the referee's option, they may also have a chance of getting lost.
High winds: Movement rates are halved. Missile fire and flight are impossible. At sea, may be used to increase the sailing speed of ships by 50%, if they travel with the wind. In sandy areas, may cause a sandstorm, reducing visibility to 20'.
Rainy: -2 penalty to missile attacks. Mud forms in 3 turns, halving movement rates.
Snowy: Visibility drops to 20'. Movement rates are halved. Bodies of water may freeze. After the snow thaws, mud remains and still impedes movement.
Tornado: The caster can direct the tornado, which moves at 120' per round. The tornado can be directed to attack, using the stats for a 12 HD air elemental (see B/X Essentials: Monsters). Ships caught in a tornado have a 75% chance of suffering 12 points of hull damage.