I noticed last year that several tour operators were planning to "extend the season" in popular Mediterranean resorts by offering holidays right through to the end of October in places where the season traditionally ends at the end of September.
This may well of course be in response to a demand for holidays abroad in the autumn half term which is usually the last week of October and sometimes overlaps into November.
These are summer destinations. There are threads on here almost daily asking whether it will be warm in October in Ibiza or Corfu or Spain.
Most posters want a family beach holiday where the DC can swim in a pool or the sea in warm sunshine.
Yes it can be good weather at that time of year but there is also a high risk of rain and cool weather, something like the UK in summer. Some islands in particular can be very wet in October.
If you want guaranteed hot sunny weather you need to go further south.