[daw___]

I'm not really sure what I am looking at.

EDIT: Now I am. Clever!

[bobongo]

I still am not. Could you explain?

[laszlokorte]

2d lookup table for (month,day) -> weekday

[knolax]

To find the current day of the week, look at the row corresponding to the day of the month and the column corresponding to the month. There's a typo for the days 18-21 where there's two 18s.