The instinct is to book a Mediterranean yacht in July or August, when prices peak and every marina turns into a scrum. But September arguably does the job better: the sea stays warm, the sun keeps shining, and the coastal towns that make this stretch of water famous haven't rolled up the awnings for winter.
The French Riviera is a natural starting point. Cannes, Antibes, Saint-Tropez and Monaco all still hum along in early autumn, and the geography works in your favour — a long lunch in Cannes, a swim off the Lérins Islands, then a lazy afternoon cruising towards Saint-Tropez is entirely doable in a single day. Or do none of it and stay on deck. The point of a private charter is that nobody is checking your progress.
Further east, the Greek Islands enter their best-kept-secret phase in September. Mykonos and its neighbours still have plenty going on, but a yacht lets you push past the obvious stops to quiet beaches and empty anchorages. The advice from charter regulars is consistent: resist the urge to island-hop yourself into exhaustion. A week crammed with seven islands usually means you remember none of them. Anchoring somewhere beautiful for an entire afternoon is often the better call.
It's worth remembering that the boat itself is half the holiday, not just transport between restaurants. Modern charter yachts come kitted out with water toys, jacuzzis and sun decks, and the crew handle everything from meals to the day's route. Good service on a charter is understated — things happen before you notice they needed doing.
The real argument for September, though, is flexibility without the crowds. You can spend one day exploring Riviera towns, the next doing absolutely nothing, and change the plan at breakfast if the mood strikes. There's no prize for the busiest itinerary.
For anyone considering it, the practical advice is to work backwards from the holiday you actually want before choosing a boat: group size, destination and how you plan to fill the days will narrow the options fast. September is also a good month to look at shorter day charters as well as full-week bookings, especially along the Riviera, where day-trip options are plentiful. Prices tend to soften after the peak season, and berth availability in the marinas improves too — both quiet advantages of travelling after the school holidays.