Hundreds of thousands amassed at the 2,300 year old city of Teotihuacan 50 kilometers north of the capital, with its massive Pyramid of the Sun and Pyramid of the Moon, to mark the equinox at 12:26 pm local time.
They climbed to the apex of the pyramids to get closer to the cloud-filtered sun, which archaeological authorities have limited this year to just five minutes at the top.
Many dressed in white and undertook early tribal rituals, meditating with herbs and incense as they sought to recharge themselves with the sun's energy.
On the Yucatan peninsula, tens of thousands were expected to visit the Mayan pyramid of Kukulkan.
At the moment of the equinox, the sun's rays generate a shadow of seven triangles on Kukulkan which look like a serpent descending the staircase.