When to go. . .
WWhen you go depends more on when you have free time. If in the summer, expect to be so packed. Keep in mind that St. Tropez is a village that, excluding tourists, has a little less than 4,000 inhabitants. In July and August it could welcome around six million visitors, with up to 30,000 people a day on Pampelonne’s main beach. In short, you will queue and pay. But that only underscores the fact that you’re in a summertime hotspot that’s nowhere groovier in Europe. If that’s your thing, summer St Trop is your place.
If you want less hustle and bustle but still want some warmth and a chance to find most of it open then the shoulder months – May, June, September, October – are for you.
However, I prefer winter when nobody but locals is about, you need a coat, quaint palaces are closed and St Tropez reverts to what it used to be – a charming little Mediterranean port village.
https://www.telegraph.co.uk/travel/destinations/europe/france/cote-d-azur/saint-tropez/articles/st-tropez-travel-guide/ An expert guide to St Tropez