//create a date of John
$birth_date = mktime(0,0,0,1,6,1991);
//determine if John's birthday has passed this year
if (date("m",$birth_date) > date("m")
&& (date("d",$birth_date) > date("d"))){
$year = date("Y");
}else {
$year = date("Y")+1;
}
//find his next birthday
$next_birth_date = mktime(0,0,0,
date("m",$birth_date),
date("d",$birth_date),
$year);
//echo the day of his next birthday
echo date('l', $next_birth_date);
Here this code might need some tweaking but it should work. And here is a link of how I figured it out: http://php.net/manual/en/function.date.php