Kyttias' posts have helped me immensely but it seems I hate to leave well enough alone.
Here's code for more specific seasons:
PHP Code:
if(new DateTime() < new DateTime($dateTime->format('Y').'-3-20 00:00:00')) $season = 'winter';
else if (new DateTime() < new DateTime($dateTime->format('Y').'-6-21 00:00:00')) $season = 'spring';
else if (new DateTime() < new DateTime($dateTime->format('Y').'-9-22 00:00:00')) $season = 'summer';
else if (new DateTime() < new DateTime($dateTime->format('Y').'-12-20 00:00:00')) $season = 'fall';
else $season = 'winter';
$document->add(new Comment("It is {$season}!"));