Yahrzeit candles should be lit the evening before the date specified. This is because the Jewish day actually begins at sundown on the previous night.
Prayer on Lighting a Yahrzeit Candle
Eternal Rock of Ages
In hushed reverence, I kindle this memorial lamp in loving remembrance on this anniversary of my beloved’s death. We have been taught that human souls are Thy candles. Through them Thou bringest light into the world. For the light of compassion and tenderness which my loved one brought into my life, I am everlastingly grateful. Help me, O G-d, to use the sacred memory of my loved one noble spur to consecrated living. May I perpetuate and transmit everything that was beautiful and loving about my loved one’s character. Keep firm my faith that we cannot go where You are not, and where You are all is well. Amen.
As the light is kindled say:
“Zecher tsaddik leevrachah.” The memory of the upright is a source of blessing.