Thai Pongal (Tamil: தைப்பொங்கல்) is a harvest festival celebrated by Tamilians in the Indian state of Tamil Nadu, the Indian Union Territory of Pondicherry. and Sri Lanka. This South Indian festival, Thai Pongal, is timed by an astronomical event - the winter solstice. Pongal is traditionally dedicated to the Sun God Surya, and marks the beginning of the northward journey of the Sun from its southernmost-limit, a movement traditionally referred to as uttarayana. It coincides with the festival Makara Sankranthi celebrated throughout India as the winter harvest, and is usually held from January 13–15 in the Gregorian calendar i.e. from the last day of the Tamil month Maargazhi to the third day of Thai. This also represents the Indic solstice when the sun purportedly enters the 10th house of the Indian zodiac i.e. Makaram or Capricorn.

The saying "Thai Pirandhal Vazhi Pirakkum" (தை பிறந்தால் வழி பிறக்கும்) meaning "the commencement of Thai paves the way for new opportunities" is often quoted regarding the Pongal festival. Pongal Tamils thank the Sun god (கதிரவன்) for the good harvest and consecrate the first grain to him on this 'Surya Mangalyam'. Tamilians decorate their homes with banana and mango leaves and embellish the floor with decorative patterns drawn using rice flour.