Position of Ios

In Ios, belonging to the Cyclades Islands, and on the nearby island of Sikinos, the climate is Mediterranean, with mild and rainy winters and warm and sunny summers. The daily average temperature ranges from 10.5 °C (51 °F) in January to 24 °C (75 °F) in July.
Here are the average temperatures.
Ios - Average temperatures
Min (°C)889121519212119161310
Max (°C)131315182226272624211815
Min (°F)464648545966707066615550
Max (°F)555559647279817975706459

The island is windy, and in summer it is cooled by a frequent wind blowing from the north. The wind has been exploited for centuries by windmills, while in recent times the waves generated by the wind are appreciated by surfers, especially on the north coast.
Precipitation follows the Mediterranean pattern, so it is concentrated from October to March, and it's not abundant, since it amounts to about 500 millimeters (20 inches) per year, and this is confirmed by the aridity of the landscape. In summer it practically never rains.
Here is the average precipitation.
Ios - Average precipitation

The interior of the island is occupied by hills, whose highest point, Pyrgos, reaches 711 meters (2,333 feet).

Winter, from December to mid-March, is mild, quite rainy and windy. The wind, frequent and sometimes intense, exacerbates the feeling of cold. Sometimes, cold air from the Balkan Peninsula can arrive here, and there can be cold days, with highs below 10 °C (50 °F), and sometimes even snow can fall.

Spring, from mid-March to May, is mild and sunny, with the rain gradually becoming more rare, and also quite windy. By mid-May, the Meltemi starts to blow, a persistent wind, cool and dry, blowing from the north for a few days in a row, especially in the daytime, but sometimes even at night.

Summer, from June to mid-September, is warm and sunny, but also windy. The Meltemi blows for long periods, especially in July and August, and it's stronger in the afternoon but can insist also in the evening. With this wind, the maximum temperature remains almost always below 30 °C (86 °F), and even in the hottest periods, when in other parts of Greece the temperature can reach or exceed 40 °C (104 °F), here it generally doesn't go over 34/35 °C (93/95 °F).

Autumn, from mid-September to November, is initially warm and sunny, but gradually becomes cooler and rainier. Autumn too is a windy season because of the southern wind, which is brought by low pressure systems coming from the Atlantic Ocean or the Mediterranean Sea.

Mylopota beach

The amount of sunshine in Ios is great in summer, when blue skies prevail, while it's not high from November to February, when the sky is often cloudy, although sunny days may occur also in midwinter.
Here are the average daily sunshine hours in nearby Naxos.
Naxos - Sunshine

The temperature of the sea is never very high, however, it reaches a maximum of 23/24 °C (73/75 °F) from July to September; in June, it's still a bit cool, about 21 °C (70 °F).
Here are the average sea temperatures.
Ios - Sea temperature
Temp (°C)161515161821232423221917
Temp (°F)615959616470737573726663

Best Time

The best time to go to Ios for a beach holiday is summer, from June to mid-September.
It's better to bring a sweatshirt for cool evenings, which occur mainly in June, but given the intensity of the wind, those who are sensitive to cold may feel a bit cool even in July and August, and therefore can properly equip themselves also in these months.
If you want to go on excursions, you can go in spring, in April and May, but since it's almost never very hot, normally you can stroll through the island in summer as well.

Back to the Cyclades Islands.