The climate of the Sporades, Greek islands in the Aegean Sea, is Mediterranean, with relatively mild, rainy winters and hot, sunny summers.
The main islands are:
- Skiathos
- Skopelos
- Skyros
There are also some smaller islands such as Kyra Panagia, Peristera (or Aspro), Gioura, Skantzoura, Piperi, and Tsougria.

These islands are also called Northern Sporades, to distinguish them from the Eastern Sporades, which include Chios, Ikaria, Lesbos and Samos, and also from the Southern Sporades, also called Dodecanese.

Being a short distance from the mainland, the Northern Sporades are subject to cold and windy periods in winter, especially the westernmost ones, like Skiathos and Skopelos: sometimes, even snow can fall.
For example, here are the average temperatures of Skopelos.
Skopelos - Average temperatures
Min (°C)445812161918161296
Max (°C)101113172226282825201612
Min (°F)393941465461666461544843
Max (°F)505255637279828277686154

Rainfall follows the Mediterranean pattern, and is more frequent from October to April; in summer, the rains are rare, though there can occasionally be brief showers or thunderstorms coming from the continent. For example, here is the average rainfall in Skopelos.
Skopelos - Average precipitation

The amount of sunshine in the Sporades is excellent in summer, when clear skies prevail, and it is also good in May and September, while in the rest of the year, it is not so high, since there are several cloudy periods.
Here are the average daily sunshine hours in Skiathos.
Skiathos - Sunshine

Votsi, Alonissos

The temperature of the sea in the area of the Sporades, still cold in May and cool in June, becomes high enough for swimming from July to September, when it reaches 23/24 °C (73/75 °F). Here, for example, is the sea temperature in Skyros.
Skyros - Sea temperature
Temp (°C)151414151821232423211816
Temp (°F)595757596470737573706461

Best Time

The best time to go to the Sporades Islands for a beach holiday is the summer, from June to mid-September. In June and September, and sometimes in early July, there can be some cool evenings, so it's best to bring a sweatshirt for the evening.
In May, not only the sea is cold, but sometimes there can also be some cool days, with highs below 20 °C (68 °F), especially in the first part of the month.

Back to the Greek Islands.