World sea water temperatures

Water temperature in Alonnisos in September

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Is it warm enough to swim in Alonnisos in September? Average water temperature in Alonnisos in September is 24.7°C and therefore suitable for comfortable swimming. The warmest sea in Alonnisos in September is 28.1°C, and the coldest is 21.4°C. Average high air temperature in Alonnisos in September is 25°C, and average low temperature is 16°C. To find out the sea temperature today and in the coming days, go to Current sea temperature in Alonnisos

Changes water temperature in Alonnisos in September 2025, 2024

To get an accurate forecast for the water temperature in Alonnisos for any chosen month, compare two years within a 10 year range using the chart below. In addition to the sea water temperature in Alonnisos, the selected years in the table also show the values of the maximum and minimum temperatures on each of the days of September.

You can choose any other years:

Year 1:   Year 2:


Day 2025 2024 Min Max
1 September25.4°C27°C24.6°C28.1°C
2 September25.7°C26.6°C24.7°C27.5°C
3 September26°C26.5°C24.6°C27.1°C
4 September25.8°C27°C25°C27°C
5 September25.6°C27°C24.6°C27°C
6 September25.3°C26.6°C24.8°C26.8°C
7 September25.1°C27°C24.7°C27°C
8 September25.2°C26.7°C24.4°C26.7°C
9 September25.3°C26.4°C23.9°C26.4°C
10 September25.5°C26.7°C23.8°C26.7°C
11 September25.2°C26.8°C23.8°C26.8°C
12 September25.9°C26.8°C23.6°C26.8°C
13 September25.7°C27°C23.6°C27°C
14 September25.5°C26.6°C23.5°C26.6°C
15 September25.4°C26.4°C23.7°C26.4°C
Day 2025 2024 Min Max
16 September25.5°C26.3°C23.6°C26.3°C
17 September25.3°C26.2°C23.5°C26.2°C
18 September25.2°C26°C23.5°C26°C
19 September24.8°C25.6°C23.6°C25.6°C
20 September24.6°C25.5°C23°C25.5°C
21 September24.4°C25.2°C22.7°C25.2°C
22 September24.1°C25.1°C22.9°C25.1°C
23 September24.2°C25.1°C22.7°C25.1°C
24 September24.5°C25°C22.5°C25.1°C
25 September24.3°C24.8°C22.4°C24.8°C
26 September24.1°C25.2°C22.5°C25.2°C
27 September 25.2°C22.3°C25.2°C
28 September 25.2°C22.2°C25.2°C
29 September 24.9°C21.4°C24.9°C
30 September 24.7°C21.4°C24.7°C
Alonnisos water temp chart in September

Average water temperature in Alonnisos in September over a decade

20152016201720182019
25.3°C24.2°C24.7°C25.4°C24.5°C
20202021202220232024
25.2°C25°C24.9°C24.3°C26°C

Alonnisos sea state in September

Chart comparing the height of waves in Alonnisos in September over the past years. The red line indicates the height of the waves when swimming in the sea is prohibited. To view the current sea conditions, click on the graph.

Waves height in Alonnisos in September

Weather and climate in Alonnisos in September

This data display average monthly climate indicators in Alonnisos in September based on our historical weather readings over a period of ten years. In addition to temperature, we include data on the number of rainy and sunny days so you can have all the information about your destination before your trip

  • Average HIGH temperature25°C
  • Average LOW temperature16°C
  • Average rainfall days3 days
  • Average rainfall1.8''/46mm
  • Average daylight12h
  • Average sunshine10h
  • Average UV index6

Alonnisos water temperature during other months:

You can also view information about water temperature for other months by clicking on the month button below

Where is the warm sea water in September?

Want to know where the water temperature in September is good for swimming? Select the continent of interest, the day of the month and the required water temperature

Region
Date (day and month)
Water temperature: min 16°C
 Average temperature  Maximum temperature

Temperature in neighboring cities

The nearest locations with the average water temperature in September. In addition, the maximum and minimum water temperatures for that month, recorded over the last decade, are shown

AvrMinMax
Patitiri24.7°C21.4°C28.1°C
Agnontas24.9°C21.5°C27.9°C
Panormos24.9°C21.5°C27.9°C
Skiathos25°C21.6°C28°C
Kolios25°C21.6°C28°C
Troulos25°C21.6°C28°C
Kanapitsa25°C21.6°C28°C
Koukounaries25.1°C21.6°C28°C
Paltsi25.1°C21.5°C28.1°C
Potistika25.1°C21.4°C28°C

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[1] - The "Blue Flag" is awarded to beaches which fulfill a number of criteria, including: the quality of the bathing water, which must be in accordance with the relevant European Union Directive environmental education and information and beach area management and safety.

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Our report for Alonnisos is compiled using satellite data together with in-situ observations to get the most reliable daily data of sea surface temperatures, surf forecasts, current temperatures and weather forecasts.

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