Trayodashi is the thirteenth tithi of the bright fortnight, a Jaya tithi in the fivefold grouping, associated with victory. Its presiding deity is traditionally Kamadeva, the god of love, though its most widespread observance is Shaivite: the Pradosha vrata, kept on the thirteenth tithi of both fortnights, is dedicated to Shiva and observed in the twilight hour of pradosha, held especially favourable for his worship. The waxing Moon by now is nearly full. In the panchanga Trayodashi is read as generally auspicious, and it carries a strong current of Shaiva devotion through the Pradosha observance. These are the conventions of the calendar and festival tradition, anchored to the count of thirteen lunar days from the new moon.
Kamadeva's association with the thirteenth tithi sits somewhat apart from the tithi's dominant Shaiva colouring through Pradosha, and the two associations coexist without being reconciled in most sources, an example of how a single numbered tithi can accumulate more than one deity assignment from different strands of tradition without any attempt to unify them. Pradosha itself is timed not simply to the calendar date of Trayodashi but to the specific twilight period, roughly an hour and a half before and after sunset, that falls within it, so the observance depends on a sub-division of the tithi by clock time in addition to the tithi's own boundary, a level of temporal precision the panchanga applies to relatively few observances.