can a macro do conditional formatting?

I have a sheet with 5 calenders, and i would like it if there was a macro that could change the fill color depending on which date group that day fell into.
i would need 5 similar macros.
I say a macro cos there are 5 calenders so a vba thing that covered the whole sheet would not work!
see the picture
i would like to change the dates in the top parts and have the calender day fill colors change accordingly. ( or text colour if that was easier)
each day in the calender does no which date it is!
any ideas folks?
thanks