Conditional formatting can refer to cells other than the current cell. You need to use "custom formula" option of the formatting dialog for this. The formula should be written as it works for the upper left corner of the range that you want to format. Use absolute and relative references according to the logic of formatting. Example:
this formats a range such as A2:Z; all columns are affected if the column A has the date 25th of December, 2016.
Another example (which looks like what you want to have in the sheet):
formats the rows where the date in column A falls on a Sunday.