Greece
Kos in September: weather, sea & travel advice
This month's data profile
Sea conditions lead
Kos in September is climatically well suited to beach holidays, family holidays, city breaks and active holidays and hiking. The average daily high is around 29 °C, and the sea is about 25 °C. With about 2 rainy days it is very dry.
Historical monthly averages, not a weather forecast. Individual days and years can differ substantially.
Rank among 12 monthly averages
90/100 · #2
Warmth
#3
Dryness
#4
Sun
#6
Sea warmth
#2
Published best categories: Overall, Beach, Family
Kos · SeptemberPhoto: Stimoroll · CC BY-SA 4.0Climate facts
- Average high
- 29 °C
- Average low
- 22 °C
- Sea
- 25 °C
- Rainy days (est.)
- 2 rainy days (est.)
- Sun (est.)
- 7 h/day
- Humidity
- 63 %
For your trip planning
September: less heat than August, still drier than October
Kos in September keeps the sea at 25 °C, the same as in August, while average highs drop from 32 °C to 29 °C. October is cooler again and noticeably wetter, with 45 mm of rain against 16 mm. September is among our best months overall and for beach trips. With an estimated 7 hours of sun a day, sun protection stays essential.
Climate evidence with direct month comparison
The highlighted row is the selected month. Precipitation total and rainy days are separate monthly averages.
| Month | Avg high °C | Avg low °C | Rainy days (est.) | Precipitation mm | Sun h/day (est.) | Humidity % | Wind m/s | Sea °C | Score |
|---|---|---|---|---|---|---|---|---|---|
| August | 32 | 24 | 0 | 2 | 8.9 | 60 | 3.7 | 25 | 79 |
| September (selected) | 29 | 22 | 2 | 16 | 7.2 | 63 | 3.9 | 25 | 90 |
| October | 25 | 19 | 5 | 45 | 5.2 | 67 | 3.6 | 23 | 91 |
How do the previous and next months compare?
Baseline: September (90/100)
Positive and negative values show the change from the selected month.
| Score Δ | Average high Δ | Average low Δ | Rainy days Δ | Rain Δ | Sun Δ | Humidity Δ | Wind Δ | Sea Δ | |
|---|---|---|---|---|---|---|---|---|---|
| August | -11 | +3.3 °C | +2.5 °C | -1.3 | -13.6 mm | +1.7 h | -3.1 % | -0.1 m/s | +0.7 °C |
| October | +1 | -4.1 °C | -3.2 °C | +3.3 | +29.9 mm | -2 h | +4.1 % | -0.3 m/s | -1.8 °C |
All twelve months in context
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Frequently asked questions
How warm is Kos in September?
The average daily high is around 29 °C, with an average daily low of about 22 °C.
Can you swim in Kos in September?
The sea is about 25 °C (warm).
Does it rain a lot in Kos in September?
The curated estimate is about 2 rainy days per month, not a directly measured long-term average. Total precipitation averages around 16 mm for the month. A rainy day does not mean all-day rain.
When is the best time to visit Kos?
By the climate score, May, June, September and October are the strongest months for Kos. For a beach trip: June, July, August and September. September is one of them.