Kos weather in September
September in Kos: hot, dry — one of the best months to visit.
Updated September 2026 · climate normals from ERA5 reanalysis
#1 of 12 months in Kos · #84 of 1413 destinations to visit in September · comfort 93/100 (tier S)
- Days
- 29°C
- Nights
- 23°C
- Wet days
- 1
- Sun
- 11.4 h
- Humidity
- 72%
- Daylight
- 12 h
Traveller notes on Kos in September
September is the month Kos regulars call the best of the year — 25 to 30°C, the sea still at 27°C, everything open, and nowhere near July and August's crowds. Evenings want a cardigan. The thing to understand about the wind is that it is directional rather than seasonal: the meltemi is a northerly running June to about mid-September, so it hits the north coast hardest — Tigaki and Mastihari especially — and the forum's fix is simply to switch sides of the island, Kardamena being the usual suggestion. Kos reads breezy year-round on the monthly averages, but an average smooths over exactly the local, directional effect regulars are describing, so take the coast advice over the number. In the heat most people count it a cooling breeze rather than a problem.
Other months in Kos
Forum posters describe March in Kos as genuinely unpredictable but still mild overall, sitting outside the reliably hot, dry stretch that runs roughly June through early October. Posters note showers this time of year can affect one side of the island while leaving another completely dry, reflecting how localized spring weather patterns can be here. Posters consistently recommend packing layers and a light raincoat for a March visit, ready for both sunny stretches and passing rain within the same trip. Posters generally rate March as a mild, changeable shoulder-season month for Kos, well ahead of the settled summer heat but past the harshest of the Aegean winter.
Add your own note from Kos's card on the map.
Kos climate normals — September
Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.
Crowds in Kos in September
How busy the place itself is — school and mass holidays, the months an editor tagged, and how sought-after the weather makes them. Never part of the comfort score.
Peak crowdsCharter and resort season, Summer holidays in Greece, school holidays in 3 of the markets that fill it(estimated)
Peak crowdsBusyShoulder seasonQuiet
Best months for Kos's weather
Ranked by this destination's own climate comfort score across the year — a different thing from how busy it gets (see Crowds above).
Best weatherKos's best weather comes in June, August and September — separate windows, not one continuous season.
Best weatherFair weatherToughest weather
What's on in Kos in September
Recurring seasonal events, natural spectacles, closures and holidays — curated and sourced.
- Season
Charter and resort season
1 May – 15 Oct · usuallySummer season opensCrowdedKardamena, Tigaki and Mastichari run on northern European charter flights, and the hotels, bike hire and beach bars open and close with them. Outside the season the airport goes back to a couple of Athens flights a day.
- Season
Sea warm enough
15 Jun – 31 Oct · usuallyThe Aegean here is comfortable from late June and holds into October, well after the charter flights thin. The hot springs at Therma warm a corner of the sea year round.
- Season
Meltemi
15 Jun – 15 Sep · usuallyWind seasonRiskThe northerly blows hardest through July and August, which is why the windsurf schools are on the north coast and the sheltered swimming is at Kefalos and Paradise in the south. It also cancels the small boats to Nisyros.
Nearby, and something's on
Within 300 km of Kos — a day trip or a short hop — with something on this month. Never part of the comfort score.
Where is Kos?
Kos in September — FAQ
- Is September a good time to visit Kos?
- September in Kos: hot, dry — one of the best months to visit. It ranks #1 of 12 months for Kos on SeasonMap's comfort score (93/100).
- What is the weather like in Kos in September?
- In September, Kos averages a daily high of 28.7°C and a low of 22.6°C, with about 8.1 mm of rain over roughly 0.9 rainy days.
- What is the air quality in Kos in September?
- Kos has a mean US Air Quality Index of about 56 in September.
Within 300 km: Rhodes' Moths at Petaloudes around 15 Jun – 15 Sep, and Naxos' Naxos Festival, Bazeos Tower around 1 Jul – 15 Sep.