Thundra Plateau is a location in The Legend of Zelda: Breath of the Wild. It is located within the northwest portion of Ludfo's Bog in the Hyrule Ridge region. The Plateau is well-known locally for the dark storm clouds surrounding it where a thunderstorm has been raging continuously for generations. Banji, the caretaker of Tabantha Bridge Stable, confirms that the Plateau is located within Ludfo's Bog, east of the stable. Thundra Plateau's unusual weather is not unique, as a similar storm rages over Calora Lake in the Faron province. Unbeknownst to the locals, this weather is not natural, and both storms are implied to have been raging for at least 10,000 years.
When Link first discovers this plateau, it is battered by an endless thunderstorm, and Link automatically receives the Shrine quest "Trial of Thunder", with Toh Yahsa giving him the quest (though the Adventure Log lists his name as ???). Thundra Plateau contain four statues with slots at their bases, and Link has to place an orb in front of its respective tower to complete the quest and reveal the Toh Yahsa Shrine. The plateau will start experiencing weather normally after Link enters the shrine.
Banji will make note of the dark storm clouds' disappearance, and considers it a blessing, even praising Hylia.
Unbeknownst to her and the general local population, the storm is part of a trial created by Toh Yahsa, a devoted Sheikah and follower of Hylia, to test the hero chosen by the Master Sword. The only noticeable ecological effect is that Thunderwing Butterflies, Electric Darners, Hot-Footed Frogs, and Tireless Frogs appear and thrive frequently in this area due to the continuous rainfall, though after the weather normalizes they appear frequently only during natural rain and thunderstorms.
The name Thundra comes from the word "thunder", a reference to the continuous thunderstorm that rages over the plateau.