Weather in Kefalonia in September

How September compares

September is the 3rd warmest month of the year in Kefalonia and ranks 91st of 134 destinations we compare for September - see where else is hot in September. Within Greece it is 27th of 44 (Greece in September). Against London's average high of 18.6°C in September, Kefalonia is 6.6°C warmer by day and 11.0°C warmer at night.

Daytime and night-time in September

The typical September day in Kefalonia peaks at 25.2°C, but that is an average: the warmest 10% of days reach 28.0°C or more. About 56% of days top 25°C and 1 in 111 pass 30°C. Nights average 22.2°C; one night in ten drops to 20.0°C or lower, so pack a layer for evenings. Between 1991 and 2020 the hottest September day here reached 33.2°C (2020-09-09) and the coldest night 16.5°C (2018-09-27).

Rain in September

Some rain (4-8 rainy days): about 6 days with 1 mm or more, 63 mm in total. Year to year it varies a lot - the wettest September was 2020 with 165 mm, the driest 2018 with 10 mm. Humidity averages 73%.

Sea temperature in September

The sea averages 25.0°C - warm enough to swim (22°c+). Depending on the year it ranges from 24.2°C to 26.2°C. For the warmest sea here, come in August (26.0°C).

Sunshine and daylight

Around 8.9 hours of sunshine a day (estimated from cloud cover), 12.2 hours of daylight: the sun rises about 07:20 and sets about 19:47 local time in mid-September. Average cloud cover is 27%.

Is September a good time to visit Kefalonia?

Yes - it is one of the better months: hot days, manageable rain and long sunny days. The best months for Kefalonia on our scoring are July, August, June; months averaging 25°C or more: Jul, Aug, Sep.

Warm days, with some heat at midday

Expect warm weather rather than relentless high temperatures. Days reach 25°C often enough for light summer clothing to be your main wardrobe, while hotter spells can bring 28°C or more. Humidity averages 73%, so walking around at midday may feel stickier than the temperature alone suggests. Keep more active plans for the cooler parts of the day and allow yourself shade when the sun feels strong. September suits travellers who want warmth for sitting outside and swimming but do not need very hot afternoons. It is less convincing if your ideal holiday depends on strong heat every day.

Plenty of sunshine, but leave room for rain

September brings about 8.9 hours of sunshine a day, giving you plenty of scope for outdoor plans. The catch is about 6 rainy days during the month, so packing only for dry weather would be optimistic. A light waterproof is more useful than assuming any wet weather will miss your stay. Keep swimming and outdoor plans movable rather than tying everything to a fixed day. The monthly picture supports a sunny holiday with some interruptions, not a promise of clear skies throughout. If an occasional change of plan would spoil the trip, September's rain risk deserves more weight in your decision.

A warm sea and mild evenings

The sea is a strong reason to choose September: at an average 25°C, it is warm enough for swimming rather than a bracing dip. The year-to-year range of 24°C to 26°C also makes swimming a reasonable priority for the trip, though your comfort in the water remains personal. Evenings are generally mild, with average night lows around 22°C, so heavy layers are unlikely to earn their luggage space. Pack a light extra layer for cooler nights rather than assuming every evening will feel equally warm. This combination suits travellers who want to swim by day and spend time outside after sunset.