In September the sea is warmest around Cyprus (28 °C), Malta (27 °C) and Comino (27 °C). Average daytime highs across the 32 islands below range from 24 °C to 31 °C; the warmest days are on Cyprus (31 °C). Every island on the list has beach weather this month. Hiking conditions (15–25 °C by day, little rain) are best on El Hierro, Leros and Pomègues. Driest: Cyprus with about 0 rain days.
| Island | Sea | Day | Night | Rain days | Good for |
|---|---|---|---|---|---|
| Cyprus | 28° | 31° | 22° | 0 | Swim |
| Malta | 27° | 28° | 23° | 5 | Swim |
| Comino | 27° | 28° | 23° | 5 | Swim |
| Gozo | 27° | 28° | 23° | 4 | Swim |
| Formentera | 27° | 28° | 22° | 8 | Swim |
| Mallorca | 26° | 28° | 20° | 9 | Swim |
| Ibiza | 26° | 28° | 22° | 7 | Swim |
| Corfu | 26° | 27° | 21° | 9 | Swim |
| Ithaca | 26° | 26° | 20° | 7 | Swim |
| Menorca | 26° | 26° | 21° | 6 | Swim |
| Crete | 26° | 28° | 21° | 4 | Swim |
| Ischia | 25° | 26° | 21° | 9 | Swim |
| Capri | 25° | 26° | 20° | 9 | Swim |
| Kos | 25° | 26° | 20° | 1 | Swim |
| Santorini | 25° | 26° | 21° | 1 | Swim |
| La Palma | 25° | 28° | 21° | 5 | Swim |
| El Hierro | 24° | 24° | 18° | 3 | SwimHike |
| Leros | 24° | 25° | 20° | 1 | SwimHike |
| Tenerife | 24° | 26° | 20° | 1 | Swim |
| Île Sainte-Marguerite (also Île Saint-Honorat) | 24° | 26° | 18° | 5 | Swim |
| La Gomera | 24° | 28° | 21° | 1 | Swim |
| Gran Canaria | 24° | 28° | 22° | 2 | Swim |
| Lavezzi Islands (also Cavallo, Île de Piana) | 24° | 26° | 20° | 6 | Swim |
| Île du Levant | 24° | 25° | 18° | 6 | Swim |
| Port-Cros | 24° | 25° | 18° | 6 | Swim |
| Porquerolles | 23° | 26° | 18° | 6 | Swim |
| Lanzarote | 23° | 28° | 21° | 1 | Swim |
| Fuerteventura | 23° | 26° | 21° | 1 | Swim |
| Île du Gaou | 23° | 25° | 18° | 6 | Swim |
| La Graciosa | 23° | 25° | 20° | 2 | Swim |
| Île des Embiez | 23° | 25° | 18° | 6 | Swim |
| Pomègues (also Frioul Islands, Ratonneau) | 22° | 24° | 17° | 5 | SwimHike |
Sources: ERA5 reanalysis via Open-Meteo (air temperature, rain; 10-year average) and Open-Meteo Marine API (sea surface temperature; 3-year average). Data by Open-Meteo.com (CC BY 4.0). Area averages — individual years vary.
Other months
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All islands, all months: sea temperature at a glance