The best time to visit the Greek Islands
The best time to visit the Greek Islands for warm, sunny weather is June to September, when its destinations average a Sunshine Score of 94/100 with daytime highs around 24°C / 75°F. May and October 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 | 24 | 12° / 54°F | 114 mm | 18° | Poor |
| February | 26 | 12° / 54°F | 89 mm | 17° | Mixed |
| March | 38 | 13° / 55°F | 57 mm | 17° | Mixed |
| April | 56 | 15° / 59°F | 35 mm | 18° | Very good |
| May | 84 | 19° / 66°F | 22 mm | 19° | Excellent |
| June | 94 | 23° / 73°F | 11 mm | 23° | Excellent |
| July | 95 | 25° / 77°F | 5 mm | 25° | Excellent |
| August | 95 | 26° / 79°F | 5 mm | 27° | Excellent |
| September | 91 | 23° / 73°F | 28 mm | 25° | Excellent |
| October | 83 | 20° / 68°F | 56 mm | 23° | Excellent |
| November | 59 | 17° / 63°F | 82 mm | 21° | Very good |
| December | 34 | 13° / 55°F | 114 mm | 19° | Mixed |
When to go — and when to think twice
Best overall: June to September — the Greek Islands' warmest, most reliable stretch (Sunshine Score 94/100, ~24°C / 75°F days). Shoulder season: May and October — quieter, still sunny. Hottest: August, ~26°C / 79°F. Wettest: January (114 mm) — pack for showers.
Where to base yourself for sunshine: Kalymnos (3,154 h/yr), Leros (3,154 h/yr), Kos (3,110 h/yr). Compare them on the sunniest Greek island guide, or open any of its destinations: Kalymnos · Leros · Kos · Samos · Astypalaia · Kastelorizo · Ikaria · Karpathos · Chios · Kasos · Rhodes · Mykonos · Naxos · Syros · Paros · Santorini · Milos · Kithira · Limnos · Zakynthos · Skiros · Mytilene · Heraklion · Kefallinia · Skiathos · Chaniá · Corfu.