Keflavík Weather in September
What's the weather like in Keflavík (Southern Peninsula) in September 2025?
The climate in Keflavík during September can be summarized as cool and a little damp.
September is in the fall / autumn in Keflavík and is typically the 4th warmest month of the year. Daytime maximum temperatures average around a cool 10°C (50°F), whilst at night 5°C (41°F) is normal.
| Daytime temperature | 9.8°C 49.7°F |
|---|---|
| Nightly temperature | 5.2°C 41.3°F |
| Average temperature | 7.5°C 45.5°F |
| Daily sunshine | 4 hrs |
| Avg rainfall | 98 mm 3.9 ins |
| Rainy days | 18 days |
| Sea temperature | 9.5°C 49.1°F |
| Humidity | 81% |
| Windspeed | 20.5kph 13 mph |
On average September is the 6th driest month of the year in Keflavík with around 98mm 3.9 inches of rain making it a a little damp time to visit. This rainfall is typically spread over 18 days, although this may vary considerably.
On the flip side this corresponds to an average of 4 hours of sunshine per day.
September temperatures in Keflavík
September rainfall
September hourly sunshine
The data used in these monthly averages covers a period of over 100 years right up until last year. As such they are a valid prediction of what to expect for the weather in Keflavík in September 2025.
Other monthly averages
Best places to visit in September
Keflavík weather stats
| Hottest month: | July | 12.9°C 55.2°F |
|---|---|---|
| Driest month: | July | 67mm 2.6ins |
| Sunniest month: | May | 3hrs |
| Coldest month: | January | 1.9°C 35.4°F |
| Wettest month: | October | 125mm 4.9ins |
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