On Yama Deepam, the Diwali lamp is placed facing south.
Yama Deepam, also called Yama Dipadana or Jam ke Diya in some traditions, is a ritual lamp associated with Yama, the Hindu deity linked with death and moral order. The lamp is traditionally placed outside or toward the rear of the home and oriented south, the direction conventionally associated with Yama.
The ritual is commonly observed around Dhanteras, the thirteenth lunar day that begins the Diwali period in many parts of India. Devotees may use an earthen lamp filled with sesame oil; some descriptions also specify a lamp shaped from wheat flour. The practice is believed to honor Yama and protect household members from untimely death.
This direction is a ritual exception to the general preference in many Hindu lamp-lighting customs for auspicious orientations such as east or north. Practices vary by region, family, and religious tradition, so the exact timing, location, number of lamps, and materials can differ even though south is the standard answer for Yama Deepam.