Alonissos Weather

The weather in Alonissos is the same as in the rest of the other northern Sporades (Skiathos and Skopelos). It is characterized by mild winters with frequent rainfalls and warm summers with quite high temperatures, cooling thanks to the blowing meltemi (north winds) during late July and early August.

In brief, the island is excellent for a visit from May to October. Temperatures reach their peak during July and August.

Below, you can see the average temperatures in Alonissos by month. We have also gathered information regarding the weather by month.

Average High & Low Air Temperature (in °C/°F)

 

Discover the weather in Alonissos by month:
January | February | March | April | May | June | July | August | September | October | November | December

January is the coldest month in Alonissos, with low temperatures and a rainy climate.

The average temperature is 11.6°C/52.8°F (maximum: 13.4°C/56.1°F | minimum: 9.9°C/49.8°F).
On the coldest nights of the month, the temperature may drop to 0°C/32°F.
On the warmest days, the temperature may reach 22°C/71.6°F.
The sunshine lasts approximately 3.5 hours.
Humidity reaches 72%, while the mean speed of the wind is around 22.1 kph (13.7 mph).
The mean sea temperature is about 14.2°C/57.5°F; hence, swimming is not recommended.

February has similar temperatures and sunlight hours to those of January.

The average temperature is 11.8°C/53.2°F (maximum: 13.7°C/56.6°F | minimum: 10°C/50°F).
On the coldest nights of the month, the temperature may drop to 0°C/32°F.
On the warmest days, the temperature may reach 23°C/73.4°F.
The sunshine lasts approximately 4 hours.
Humidity reaches 70%, while the mean speed of the wind is around 21.8 kph (13.5 mph).
The mean sea temperature is about 14°C/57.2°F; hence, swimming is not recommended.

Temperatures are slightly higher during March, however, rainfall and humidity persist.

The average temperature is 13.1°C/54.9°F (maximum: 14.9°C/58.8°F | minimum: 11.4°C/52.5°F).
On the coldest nights of the month, the temperature may drop to 3°C/37.4°F.
On the warmest days, the temperature may reach 26°C/78.8°F.
The sunshine lasts approximately 5.5 hours.
Humidity reaches 69%, while the mean speed of the wind is around 19.3 kph (11.9 mph).
The mean sea temperature is about 14°C/57.2°F; hence, swimming is not recommended.

April is warmer than March, but the sea waters are still chilly.

The average temperature is 15.2°C/59.3°F (maximum: 16.9°C/62.4°F | minimum: 13.5°C/56.3°F).
On the coldest nights of the month, the temperature may drop to 9°C/48.2°F.
On the warmest days, the temperature may reach 30°C/86°F.
The sunshine lasts approximately 7 hours.
Humidity reaches 65%, while the mean speed of the wind is around 15.9 kph (9.8 mph).
The mean sea temperature is about 15°C/59°F; hence, swimming is not recommended.

May is the start of warmth in Alonissos and a good time to visit the island, with many seasonal establishments opening up.

The average temperature is 19.3°C/66.7°F (maximum: 20.9°C/69.6°F | minimum: 17.7°C/63.8°F).
On the coldest nights of the month, the temperature may drop to 11°C/51.8°F.
On the warmest days, the temperature may reach 30°C/86°F.
The sunshine lasts approximately 9 hours.
Humidity reaches 65%, while the mean speed of the wind is around 13.7 kph (8.5 mph).
The mean sea temperature is about 18°C/64.4°F; hence, the waters are a bit cool.

June signals the beginning of summer with less rain, warmer waters, and higher temperatures.

The average temperature is 23.6°C/74.4°F (maximum: 25.1°C/77.1°F | minimum: 22.1°C/71.7°F).
On the coldest nights of the month, the temperature may drop to 17°C/62.6°F.
On the warmest days, the temperature may reach 39°C/102.2°F.
The sunshine lasts approximately 10.5 hours.
Humidity reaches 61%, while the mean speed of the wind is around 12.8 kph (7.9 mph).
The mean sea temperature is 22.2°C/71.9°F; hence, the waters are warm.

July is one of the two warmest summer months in Alonissos. The temperatures are at their highest and the sea waters are pleasantly warm and ideal for a refreshing swim.

The average temperature is 26.1°C/79.9°F (maximum: 27.6°C/81.6°F | minimum: 24.6°C/76.2°F).
On the coldest nights of the month, the temperature may drop to 21°C/69.8°F.
On the warmest days, the temperature may reach 39°C/102.2°F.
The sunshine lasts approximately 11.5 hours.
Humidity reaches 58%, while the mean speed of the wind is around 14.1 kph (8.7 mph).
The mean sea temperature is 24.7°C/76.4°F; hence, the waters are very warm.

August's weather is the direct continuation of July, with high temperatures and a dry climate.

The average temperature is 26.5°C/79.7°F (maximum: 28°C/82.4°F | minimum: 25°C/77°F).
On the coldest nights of the month, the temperature may drop to 22°C/71.6°F.
On the warmest days, the temperature may reach 37°C/98.6°F.
The sunshine lasts approximately 11 hours.
Humidity reaches 60%, while the mean speed of the wind is around 15.2 kph (9.4 mph).
The mean sea temperature is 25°C/77°F; hence, the waters are very warm.

September is the start of autumn, though the weather retains its warmth, making this a good time to visit if you want to avoid bigger crowds.

The average temperature is 23.7°C/74.6°F (maximum: 25.3°C/77.5°F | minimum: 22.2°C/71.9°F).
On the coldest nights of the month, the temperature may drop to 17°C/62.6°F.
On the warmest days, the temperature may reach 33°C/91.4°F.
The sunshine lasts approximately 8.5 hours.
Humidity reaches 64%, while the mean speed of the wind is around 15.8 kph (9.8 mph).
The mean sea temperature is 23.7°C/74.6°F; hence, the waters are warm.

October officially marks the end of the tourist season, however, temperatures are still pleasant and the sea is good for swimming.

The average temperature is 20.1°C/68.1°F (maximum: 21.7°C/71°F | minimum: 18.5°C/65.3°F).
On the coldest nights of the month, the temperature may drop to 12°C/53.6°F.
On the warmest days, the temperature may reach 30°C/86°F.
The sunshine lasts approximately 5.5 hours.
Humidity reaches 70%, while the mean speed of the wind is around 17.8 kph (11 mph).
The mean sea temperature is 20.7°C/69.2°F; hence, the waters are warm.

November sees colder temperatures and a decrease in sunlight hours.

The average temperature is 16.4°C/61.5°F (maximum: 18.1°C/64.5°F | minimum: 14.8°C/58.6°F).
On the coldest nights of the month, the temperature may drop to 6°C/42.8°F.
On the warmest days, the temperature may reach 25°C/77°F.
The sunshine lasts approximately 4 hours.
Humidity reaches 74%, while the mean speed of the wind is around 19.6 kph (12.1 mph).
The mean sea temperature is 17.7°C/63.8°F; hence, the waters are cool.

Alonissos gets colder and windier in December, with lower day-to-day temperatures and more frequent rainfalls.

The average temperature is 13.1°C/55.5°F (maximum: 14.9°C/58.8°F | minimum: 11.4°C/52.5°F).
On the coldest nights of the month, the temperature may drop to 3°C/37.4°F.
On the warmest days, the temperature may reach 19°C/66.2°F.
The sunshine lasts approximately 3.5 hours.
Humidity reaches 73%, while the mean speed of the wind is around 21.5 kph (13.4 mph).
The mean sea temperature is about 15.5°C/59.9°F; hence, swimming is not recommended.