She first appeared in the episode "Leonardo Versus Tempestra". She was originally a computer generated image from a video game called "Tempestra's Revenge," which Leonardo had become obsessed with due to being unable to beat it. She became a living being when during lightning strikes while the game was being played by Leonardo. He contacts the other Turtles and asks them for help. Tempestra overhears him calling for help and traps the other Turtles in their lair by flooding the sewers.
April O'Neil finds Leonardo in the middle of an earthquake that Tempestra has started. The fearless reporter picks up the dazed Ninja Turtle and they both set out to find Tempestra. They follow her trail to a nuclear power plant where she has gone to recharge herself. Leonardo thinks he has an idea to get rid of Tempestra for good. He tries to egg her on by telling her he does not think she is all that powerful. Tempestra falls for the trick and drains her remaining her strength by creating three creatures to fight Leonardo.
The other three Turtles escape the flooded sewer and arrive at the power plant just as Tempestra releases her creatures upon Leonardo. With all the Turtles reunited, they defeat the monsters with ease.
Tempestra realizes that she has been tricked, and tries to blow up the nuclear generator to get more power. She was defeated by Leonardo when he used the computer circuit board from the now wrecked video game machine to capture her.
She later returns later on in the series in "Night of the Rogues" as one of the Rogues assembled by Shredder, a group of former enemies of the Turtles whom Shredder had brought together with the intention of destroying them, and in return he offered them all payment for their services. Tempestra served as the leader of the group. It is unknown how she escaped the circuit board she was trapped, or even how Shredder knew about her, in except that Shredder likely brought her from Dimension X. She is not seen anywhere on Earth after the group fled following the destruction of their payment for destroying the Turtles.
Powers and Abilities
She can control the weather (mostly manifesting through wind and lightning attacks), and seems to have telekinetic powers.