Navel Oranges stay yellow?

I have a 5 year old dwarf naval orange tree. It has started to produce a lot of fruit but they have not turned "orange" but are staying "yellow". We are in the middle of "rain season" on the Central Coast of CA, but I fertilized in December with "Jobs Stakes". Any words of wisdom or advice?

Thanks,

ML

 

Sometimes, months can go by before the true colour of the citrus fruit is true...