Conditional formatting based on dates

Massive long shot here.....I'm trying to conditionally format certain cells to black out after the end of a certain month.

It is for a monthly time sheet spreadsheet and I have so far been able to get the cells to update to the correct day/date when any date is entered into a particular cell. Eg I enter the date 01/2014 in one cell and then the day if the week and the date shows up in 2 other rows of cells. This works great for when there are 31 days in the month but when the month only has 28 days the dates carry on in to the next month untill the 3rd.
I want to be able to blank out those days that roll over into the next month.
Hope I have explained myself apologies for the rambling message!
Thanks in advance Amy