Weather in Skiathos, Skopelos, and Alonissos
The Climate of the Northern Sporades
The Northern Sporades are an island chain stretching across the southern part of the North Aegean. Their geographic location leaves them exposed to both north and south winds, while Psathoura, the easternmost island, is also vulnerable to eastern weather systems. Due to the proximity of Mount Pelion to the west, they are generally protected from western systems.
Spring and Summer Weather in the Northern Sporades
In early spring (March), cold fronts from the Balkans create strong north-northeasterly winds, which are gradually replaced by southern systems throughout April and May. By late spring and early summer (May – June), winds are generally light, with local breezes blowing in the afternoon. Starting in mid-summer (July) and into August, the “Meltemi” winds begin to blow, overriding the local breezes. The Meltemia are strong NE winds that intensify in the midday and afternoon and weaken at night. In the fall (September – October), these winds gradually fade, and by late autumn, the first cold fronts and north winds signal the coming of winter.
Rainfall in the Sporades
Regarding rainfall, the northern sections receive a fair amount in the spring. By late spring and early summer, local clouds often develop in the midday and afternoon, leading to brief showers, especially in the western areas. In late summer and early autumn, local thunderstorms can affect the islands in the late afternoon and early evening hours.
Generally, temperatures do not drop very low in the spring. In the summer, coastal breezes and the Meltemia significantly influence the climate, making it milder with lower maximum temperatures than the nearby mainland.
Because of the islands’ geography, they are affected differently by various weather systems. However, since there are numerous natural anchorages beyond the main ports, a suitable and safe spot can always be found.
What to Look Out For
Skiathos: When the wind is from the north, it affects the main port with wind but no significant swells. However, it makes mooring at Lalaria and the intermediate sections near the small Skantzoura islets impossible, or can cause a surge (ground swell) at Koukounaries. When the wind is from the south, the main port is unaffected, but the western and southwestern areas do not provide safe anchorage.
Skopelos: Weather significantly affects the area just outside the entrance to the main harbor during north winds or afternoon breezes. All other ports and mooring bays on the south and west sides of the island remain unaffected. Southern winds do not affect the main harbor but can create difficulties at the entrances of Agnontas and Stafylos.
Alonissos: A north wind brings a surge into the main harbor but leaves southern mooring areas (e.g., Steni Vala, Tzortzi, Milia, etc.) unaffected. A south wind creates heavy swells in the main harbor and the southwest of the island, along with a surge that weakens as you move east. Vasiliko on Peristera island remains well-protected from all weather conditions, as does Gerakas, provided you make it inside the bay in time.
Kyra Panagia: The “Planitis” bay is completely protected from all weather conditions once inside; however, its entrance is hit by heavy swells during northern systems. At Agios Petros, a surge enters when there is a strong northern current, while southern winds make the area unsuitable and unsafe for mooring.