Maybe you could try something like this:
$('#calendar').fullCalendar({
defaultView: 'month',
events: [{
title: 'Some quite long event description in a day cell',
start: '2017-01-05',
end: '2017-01-09',
rendering: 'background',
allDay: true
}],
eventAfterAllRender: function(view) {
$.each($('#calendar').fullCalendar('clientEvents'), function() {
var event = this;
var $start = $('#calendar').find('td.fc-day[data-date="' + event.start.format('YYYY-MM-DD') + '"]');
var $end = $('#calendar').find('td.fc-day[data-date="' + event.end.format('YYYY-MM-DD') + '"]');
if (event.rendering === 'background') {
for (var d = event.start; d <= event.end; d.add(1, 'day')) {
$('#calendar').find('td.fc-day[data-date="' + d.format('YYYY-MM-DD') + '"]').append('<a href="test.html">' + event.title + '</a>');
}
}
});
}
});
Check this fiddle.
I noticed that you would like to have an event title below day number. Solution above is a bit different, but it should give you an idea how it could be done I hope.