Meteo Ajaccio (Corsica) in agosto

Corsica's population roughly triples in August - regulars put it near a million against 280,000 in winter - because the back half of July and all of August is when France takes its holiday, and Italian families arrive on top. Their verdict is that it is genuinely crowded but never resort-crowded in the Ibiza sense: these are extended families, not stag parties. On heat they call 28 to 32C standard with the occasional spell to 40, and the sea properly warm. The practical advice is to stay somewhere you do not need a car to reach the beach, which is what makes an August week bearable. September and October are the months they would rather send you. The record: 30.2C days feeling like 33C, 19.1C nights, 1.8 precipitation days, 12.6 hours of sun and a 25.4C sea.

Regulars are specific this month brings roughly twice the rainfall of September, some very heavy showers a real possibility even on a trip that also gets a full week of unbroken sunshine. Our row backs that mild, genuinely wet read, 23.6C over 12.9C nights feeling 13C, with 73.9mm of rain across 6.8 days and humidity at 77 percent. Regulars are honest September reads as the statistically better month overall, though plenty of visitors have spent a trip here in October and loved every part of it regardless. The sea sits at a warm 22.9C, still genuinely swimmable this late in the season. The record: 9 hours of sun, a 16.4 kph wind and AQI 36.

May is the island's walking month rather than its swimming one, and the board separates the two cleanly. Late April to early June is the best window for the trails - by early May everything but the highest sections of the GR20 is clear of snow, though a shower up there is still possible - while on the sea they are blunt: unless you are insensitive to cold, you will be lucky to find it warm enough. Our column agrees at 18.5C, against air of 22.5C reading as 24C and nights at 12.4C. Their other warning is about altitude: one May day can be 25C in the sun down here and hail at freezing up there. Rain is 49.1mm across 5.3 days. The record: humidity 77 percent, 12 hours of sun and AQI 42.

Regulars call September the loveliest month here and split it in two. The first half is still summer weather with the crowds already leaving, since high season is mid-July to the end of August and the beaches quieten from about the middle of the month. The second half turns less stable - showers grow more frequent and the temperature slips - but the shops, bars and restaurants are all still open, and only the small-town beach services start closing at the very end. The warm sea keeps the coastal nights mild: 23.6C water against 27.3C days and 16.3C nights. Rain stays light at 42.1mm across 4.6 days. The record: humidity 74 percent, 10.6 hours of sun and a 15.4 kph wind.

Corsica regulars prefer June to July and give a date rather than a feeling: the French school holidays start around the 5th of July, so the island does not get properly busy until then. June is less hot, less crowded and a little cheaper for the same coast. Our row's 27.7C over 16.8C reads as 31C by day with 23.3mm across 2.9 precipitation days and 13.2 hours of sun, so the weather is already summer. The honest caveat is the water. They describe the June sea as still quite cool and bracing on the first entry, though swimmable; our 24C is the month's average, and early June sits below it. September is the swap for warm water with the same quiet. The record: humidity 73 percent, a 13.4 kph wind, 15.2 hours of daylight and AQI 47.