Hi, Shea/Rich.
This is an example of some data that comes from tribe_events_get_current_month_day(): https://cl.ly/317c1154f815
You could do something like this with it:
$datetime = DateTime::createFromFormat('Y-m-d', $day['date'] ); // 2018-10-04
echo $datetime->format('D'); // Thu
echo $datetime->format('l'); // Thursday
You might also want to pass the time zone, but this is just a proof-of-concept.
See https://secure.php.net/manual/datetime.createfromformat.php for more details.
Please let me know how this goes for you.