The nine colours of Navratri each stand for a particular aspect of the goddess Durga. For instance, the hues white and red are associated with her composure and purity, whilst red is associated with her power and might.
In some contexts, the choice of colour is influenced by astrological and planetary factors. Yellow and green, for instance, are associated with Venus and the Sun, respectively.
The selection of colours for Navratri might be influenced by the cultural traditions and practises of the various Indian regions. For instance, the colour pink is associated with the goddess Ambaji, a respected divinity in Gujarat.
Sharad Navratri, which falls between the monsoon and the autumn, and Chaitra Navratri, which falls between the winter and the spring, both occur when the seasons change.