Month-specific sea-surface temperature · Greece

Kefalonia Sea Temperature in May

19.4°C

66.9°F

In May, sea-surface temperature near Kefalonia has a historical monthly average of 19.4°C. This is not the reading for any particular holiday date.

Across 2023–2025, the lowest and highest yearly May monthly means were 18.8–19.7°C. These are not daily extremes.

Previous month

April · 17.1°C

Change into May: +2.3°C

Next month

June · 23.7°C

Change into next month: +4.3°C

Can you swim or snorkel in Kefalonia in May?

At 19.4°C our temperature-only guide describes the water as cool water. Comfort depends on your cold tolerance, immersion time and wind. A historical average cannot determine whether conditions are safe on any given day.

Do you need a wetsuit?

A 3 mm shorty or full wetsuit will make longer snorkels more comfortable.

Which beach should you choose?

Look for a beach sheltered from the actual forecast waves and wind on your visit. Exposure, currents and entry conditions vary even where water temperatures are similar. Follow local warnings.

Check the current waves, wind and snorkeling forecast →

A live forecast does not predict a future May. Check again close to your trip.

Nearby places in May

Comparable historical averages from independent marine grid cells. Warmer water does not imply safe snorkeling.

Data source and limitations

Source: Open-Meteo Marine API, MeteoFrance sea-surface temperature; 2023–2025. Marine model grid near 38.18, 20.56. Based on 3 yearly monthly means and 2232 recorded samples. Source methodology.

Modelled sea-surface temperatures do not establish underwater visibility, wildlife, calm currents or safe entry.