A weather modification network is a system used to alter the natural weather patterns of a planet.
A weather control net is in place on Earth and is designed to dissipate destructive weather phenomena such as tornadoes. Malfunctions are rare, such as the one created by the Q in order to execute the parents of Amanda Rogers, who had deserted the Q Continuum to live amongst humans but subsequent violated their promise not to exercise their powers. (TNG: "True Q")
Caldos II had its weather modification net installed in the mid 23rd century, when Caldos colony was established there. The net was maintained from a substation located within the colony. The net experienced several malfunctions in 2370 due to interference from the anaphasic lifeform Ronin. Ronin was using the net as a way to maintain molecular cohesion during the transition from his previous host, Felisa Howard, to his next host, Beverly Crusher. The net required a power transfer from the Starship Enterprise-D, and the Enterprise environmental controls were later affected by feedback from the transfer. (TNG: "Sub Rosa")
A weather control network was installed on Hekaras II in 2370, to counteract the effects of instability in the Hekaras Corridor caused by warp travel. (TNG: "Force of Nature")
One of the most sophisticated weather control systems known has been in place on Risa since at least the 22nd century, where it suppresses the naturally rain-soaked and dismal climate in favor of a sunny, tropical one. The system was sabotaged by the New Essentialists in 2370, with help from Lieutenant Commander Worf. Their actions were designed to make a point to the people of the Federation that the trivial pursuit of pleasure, such as on Risa, was weakening their moral fiber in the face of enemies such as the Dominion. (DS9: "Let He Who Is Without Sin...")