Which Greek island is sunniest in October?

In October, Kos scores highest for sunshine (90/100) with 21°C average daytime highs.

Which Greek island is sunniest in May?

In May, Kos leads with a Sunshine Score of 94/100 and 20°C daytime highs.

When can you swim in the sea in Greece?

The Aegean is warmest from July to October — in September the warmest island sea is Kastelorizo at 29°C; by late October it cools but often stays above 21°C.

Which is the sunniest Greek island? Month by month

Q: Which is the sunniest Greek island?

The top of the table is tightly packed: Kalymnos (3,154 h/yr), Leros (3,154 h/yr), Kos (3,110 h/yr) lead on annual sunshine, with Rhodes close behind at 2,994 h.

27 Greek island destinations — every one with its own airport — compared from long-term climate normals: the sunniest and the warmest island each month, and where the sea is warmest. Mainland Greece is on the Greece page.

The sunniest Greek island, every month

Month	Sunniest island	Score	Warmest island	Day high	Warmest sea
January	Astypalaia	38	Astypalaia	14° / 57°F	Kos 19°
February	Astypalaia	40	Astypalaia	14° / 57°F	Kos 18°
March	Santorini	51	Chaniá	15° / 59°F	Kos 18°
April	Mytilene	72	Mytilene	18° / 64°F	Kastelorizo 19°
May	Kos	94	Mytilene	22° / 72°F	Corfu 21°
June	Kos	97	Mytilene	27° / 81°F	Corfu 25°
July	Kalymnos	98	Mytilene	30° / 86°F	Corfu 28°
August	Kalymnos	98	Mytilene	30° / 86°F	Kastelorizo 30°
September	Kos	94	Rhodes	26° / 79°F	Kastelorizo 29°
October	Kos	90	Rhodes	22° / 72°F	Kastelorizo 26°
November	Santorini	70	Chaniá	18° / 64°F	Kos 23°
December	Santorini	47	Chaniá	15° / 59°F	Kos 21°

Greek islands ranked by annual sunshine

#	Island destination	Sun h/yr	Best month	Day high then
1	Kalymnos	3,154	July	26° / 79°F
2	Leros	3,154	July	26° / 79°F
3	Kos	3,110	June	24° / 75°F
4	Samos	3,110	July	27° / 81°F
5	Astypalaia	3,110	June	23° / 73°F
6	Kastelorizo	3,110	July	22° / 72°F
7	Ikaria	3,066	July	24° / 75°F
8	Karpathos	3,022	July	23° / 73°F
9	Chios	3,022	July	26° / 79°F
10	Kasos	3,022	July	23° / 73°F
11	Rhodes	2,994	June	26° / 79°F
12	Mykonos	2,978	July	23° / 73°F
13	Naxos	2,978	June	23° / 73°F
14	Syros	2,935	August	25° / 77°F
15	Paros	2,935	July	25° / 77°F

Sunshine hours come from climate normals interpolated to each island's airport — neighbouring small islands can share a value, so treat differences of under ~100 hours as a tie. How the data works →