The best time to visit the Greek Islands
The best time to visit the Greek Islands for warm, sunny weather is May to August, when its destinations average a Sunshine Score of 95/100 with daytime highs around 25°C / 77°F. April and September are quieter shoulder-season alternatives with still-reliable sun. The sea is swimmable (21°C+) about 6 months a year, warmest in August at 27°C.
The Greek Islands by month, averaged across 27 destinations from long-term climate normals — the best stretch is highlighted.
| Month | Sunshine Score | Avg day high | Rain | Sea | For a trip |
|---|---|---|---|---|---|
| January | 36 | 14° / 57°F | 114 mm | 18° | Mixed |
| February | 39 | 14° / 57°F | 89 mm | 17° | Mixed |
| March | 53 | 15° / 59°F | 57 mm | 17° | Good |
| April | 70 | 17° / 63°F | 35 mm | 18° | Excellent |
| May | 91 | 21° / 70°F | 22 mm | 19° | Excellent |
| June | 95 | 25° / 77°F | 11 mm | 23° | Excellent |
| July | 96 | 27° / 81°F | 5 mm | 25° | Excellent |
| August | 96 | 28° / 82°F | 5 mm | 27° | Excellent |
| September | 91 | 25° / 77°F | 28 mm | 25° | Excellent |
| October | 86 | 22° / 72°F | 56 mm | 23° | Excellent |
| November | 71 | 19° / 66°F | 82 mm | 21° | Excellent |
| December | 47 | 15° / 59°F | 114 mm | 19° | Good |
When to go — and when to think twice
Best overall: May to August — the Greek Islands' warmest, most reliable stretch (Sunshine Score 95/100, ~25°C / 77°F days). Shoulder season: April and September — quieter, still sunny. Hottest: August, ~28°C / 82°F. Wettest: January (114 mm) — pack for showers.
Where to base yourself for sunshine: Kos (3,218 h/yr), Rhodes (3,201 h/yr), Karpathos (3,177 h/yr). Compare them on the sunniest Greek island guide, or open any of its destinations: Kos · Rhodes · Karpathos · Kastelorizo · Kalymnos · Astypalaia · Kasos · Samos · Ikaria · Leros · Chios · Milos · Santorini · Zakynthos · Heraklion · Kithira · Mykonos · Naxos · Chaniá · Paros · Syros · Kefallinia · Mytilene · Corfu · Limnos · Skiros · Skiathos.