The Principle of a specific Deity is present in the atmosphere in a larger proportion on the day of the respective festival or is attracted to the venue where religious rituals of that Deity are being performed.
According to the Hindu lunar calendar, Shrikrushna was born on Shravan Krushna Paksha Ashtami (Eighth day of the dark fortnight of Shravan) at midnight, when the moon was in Vrushabh formation with the lunar asterism, Rohini.
Rangapanchami is celebrated on Phalgun Krushna paksha Panchami (Fifth day of the dark fortnight of the month of Phalgun). Today, at many places the festival of Rangpanchami is celebrated on the day after Holi.
Holi is a festival that guides us on the path of embracing sattvik nature by elimination of evil character and bad thoughts in ones mind. The aim is to purify the environment by offering oblation in form of dry wood to the fire.