Yopaat was an important Maya storm god in the southern Maya area that included the cities of Copán and Quiriguá during the Classic period of Mesoamerican chronology (c. 250–900 AD). Yopaat was closely related to Chaac, the Maya rain god. Yopaat is depicted as bearing a flint weapon that represents a thunderbolt. Yopaat was held responsible for especially violent lightning storms, that were believed to cause earthquakes. He was often represented with a snake in place of one leg, demonstrating a close relationship with K'awiil, another Maya deity with similar attributes.
The deity was most important during the Late Classic period (c. 600–900 AD). Although his worship was concentrated in the Motagua Valley, glyphic inscriptions of the name occur as far away as Palenque, Yaxchilán and Toniná. Decipherment of a hieroglyphic text found at Palenque has resulted in the suggestion that Yopaat was associated with mist that forms before rainfall. The name of the deity was freqently used as a part of the names of the kings of the Quiriguá dynasty, and it is likely that Yopaat was the patron god of the city, which was subject to abundant rainfall and frequent floods.