Admitted that rubin's way is much more clearer and readable, you can pass variables also interrupting and resuming the awk code by the means of single quotes, like I posted before.
The problem is that before I made a mistake, you also need to add a couple of double quotes to complicate things a little bit more
Code:
awk '$3=="'"$MONTH"'" {print $1, $2, $3, $4, $5, $6}' *.hits