Keflavík Weather in September
September in Keflavík brings low temperatures around 12°C (54°F) during the day, dropping to 8°C (46°F) at night, with the most rainfall of the year.
Rainfall in Keflavík in September
With this being the wettest month, keeping an umbrella on hand might save you from getting wet from a sudden shower. Records from the past 30 years suggest around 18 days of rain, with 149 mm (5.9 in) average for the month. This is a wet month with frequent and often heavy showers. Both the number of rain days and the total rainfall are high.
Temperature in Keflavík in September
September in Keflavík brings typical temperatures with highs around 12°C (54°F) and lows of 8°C (46°F). Temperatures remain on the cold side all day. A proper warm jacket is worth having, not just for evenings. Nights drop to 8°C (46°F). Cold nights like these are actually great for sleeping well, as long as you have a warm enough duvet.
Sunshine in Keflavík in September
You can expect a moderate amount of sunlight, with approximately 121 hours. This means a pleasant mix of sun and overcast.September in Keflavík has its charm. However, if you're seeking pleasant, dry and sunny weather, our weather planner can help you explore other destinations in the world.
Check the conditions for any month of the year.
For a detailed overview over the year and the best time to visit Iceland, check out our Keflavík's climate page.
Keflavík Temperature in September
Min Temperature
8°C (46°F)
Max Temperature
12°C (54°F)
Chance of Rain
61%
Precipitation
149 mm (5.9 in)
Rainy days
18 days
Humidity
79% *
Sunshine
121 hours *
Percentage Sunshine
30% *
Daily Historical Temperatures
50-year average (1976-2025)
Based on our historical records, temperatures in Keflavík typically stay consistent throughout September, with daily highs averaging around 12°C (54°F). Nights are cold, with lows typically ranging from 5°C (41°F) to 8°C (46°F).
Average temperatures in September
Daily Historical Precipitation
50-year average (1976-2025)
Average daily rainfall for each day of the month based on long-term records.
Average precipitation in September
Historical weather for Keflavík in September
Browse day-by-day weather records for Keflavík spanning 51 years. Select any month and year to see actual temperatures, rainfall, and conditions recorded on each day.
Keflavík historical weather extremes in September
According to our 49 years of weather records for Keflavík, the following extremes were recorded between 1976 and 2025.
- The hottest September day on record in Keflavík reached 17°C (63°F) (September 2, 2008).
- Keflavík experienced its chilliest September day on September 30, 1981, reaching only 3°C (37°F).
- Keflavík registered its coldest September night on September 25, 2020, with temperatures dropping to -1°C (30°F).
- Peak precipitation in September occurred on September 9, 2022, when 40 mm (1.6 in) of precipitation was measured.
Best Places in Iceland in September
Find out more about the weather in Iceland and which places have the best travel conditions in this month. See all of Iceland in September →
perfect weather
pleasant
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What to Wear in Keflavík in September
Pack for changing conditions in Keflavík in September. Bring a mix of short and long sleeves, a warm layer like a hoodie or light jacket, and comfortable pants. The key is being able to add or remove layers as the days goes by. Prepare for significant rainfall with proper waterproof clothing and shoes. Sunglasses could come in handy during the sunnier parts of your trip.What To Do in Keflavík in September
We rated the following activities from 1 (least suitable) to 10 (best) to do.
Check the conditions for any month of the year.
For a detailed overview over the year and the best time to visit Iceland, check out our Keflavík's climate page.
Temperature Rainfall Sunshine Humidity
See the full Keflavík climate overview or explore weather in Iceland.
