20–21 March 2027
Spring equinox at Chichén Itzá
El Castillo, Chichén Itzá
Around the equinox, the late-afternoon light draws a zigzag of shadow down the staircase of El Castillo, which looks like a serpent descending. It is best seen in the afternoon, roughly from 3 to 5 pm, and INAH runs a special operation for the huge crowds. Whether the Maya designed the effect is unknown.
Every year around 20–21 March, set by the spring equinox; INAH announces the exact access dates each year. The date changes each year by a set rule: check it before you travel. Source ↗