Keflavík, Iceland — Weather in September 2026

Climate Overview

Keflavík, Iceland in September has mild conditions, with highs averaging 10.1°C (50°F) and noticeably cooler mornings. Rain falls on about 18 days this month, totalling around 135 mm. Winds are noticeable. Sea temperature stays cool at 10.5°C (51°F).

This month falls at the beginning of Autumn.

Daily highs in September gradually drop from around 12°C (53°F) at the start to 9°C (48°F) by month's end.

September sees fairly even rainfall, totalling about 135 mm across the month.

Expect around 8.6h of sunshine at the start of September, decreasing to 6.2h by the end.

The warmest days tend to fall around the 1th, averaging 11.6°C (53°F).

Compared to August, this month is about 2°C cooler with 5 more rainy days. Temperatures begin dropping heading into October.

Monthly September Averages

Temperature

10°C / 7°C

Feels Like

6°C / 3°C

Rain

18 days · 135 mm

Sunshine

7.2h / day

Humidity

81% — Very Humid

Wind

30 km/h

Wind Direction

E (84°)

Gusts

48 km/h

Daylight

13 h

Cloud Cover

74%

Clear Sky Days

1.3

UV Index

2.2 — Moderate

Sea Temperature

11°C

Dew Point

6°C — Dry

Moon Phase

Waxing Crescent · 11%

Climate Charts

Daily averages based on historical data (2016–2025)

Daily Temperature

HighLow

Daily Precipitation

Rainfall

Daily Sunshine

Sunshine

Daily Wind Speed

Wind Speed

Sun Position

Sunrise 06:54

Daylight 13.1h

Sunset 20:00

What to Expect

Keep afternoons flexible as tropical showers are common — they typically clear within an hour.

Wet weather can spread across much of the day, so it is best to keep outdoor plans flexible.

Recent yearly records for September have stayed close to the long-run average.

Compare Months

Month	Temp	Feels Like	Rain	Sun	Humidity	UV	Status	Details
January	3°C / 0°C	-3°C / -7°C	19days (124 mm) Wet	1.4h Poor	77% Humid	0.2 Low	Wet	View Details
February	3°C / 0°C	-3°C / -6°C	18days (122 mm) Wet	3.5h Poor	78% Humid	0.8 Low	Wet	View Details
March	4°C / 1°C	-2°C / -6°C	17days (115 mm) Wet	6.7h Fair	76% Humid	1.8 Low	Poor	View Details
April	6°C / 3°C	2°C / -3°C	15days (102 mm) Wet	8.8h Good	78% Humid	3.1 Moderate	Poor	View Details
May	9°C / 5°C	5°C / 0°C	16days (101 mm) Wet	11h Excellent	78% Humid	4 Moderate	Poor	View Details
June best	11°C / 8°C	7°C / 4°C	14days (76 mm) Wet	10.9h Excellent	81% Humid	4.2 Moderate	Fair	View Details
July best	13°C / 10°C	10°C / 6°C	13days (71 mm) Wet	10.6h Excellent	84% Humid	4.1 Moderate	Fair	View Details
August best	12°C / 10°C	10°C / 6°C	13days (87 mm) Wet	9.5h Good	83% Humid	3.3 Moderate	Fair	View Details
September	10°C / 7°C	6°C / 3°C	18days (135 mm) Wet	7.2h Good	81% Humid	2.2 Moderate	Wet	View Details
October	7°C / 5°C	3°C / -1°C	18days (134 mm) Wet	4.5h Fair	81% Humid	1 Low	Wet	View Details
November	5°C / 2°C	0°C / -4°C	16days (111 mm) Wet	1.9h Poor	79% Humid	0.4 Low	Poor	View Details
December	3°C / 0°C	-2°C / -6°C	17days (112 mm) Wet	1.1h Poor	78% Humid	0.1 Low	Poor	View Details

What to Wear

Bundle up with a warm coat, scarf, and closed-toe shoes. Thermal layers underneath give flexibility between indoors and outdoors.

A waterproof jacket or compact umbrella is recommended for occasional showers.

Packing List

Layered clothingLight jacketUmbrellaWaterproof jacketWaterproof shoes

Frequently Asked Questions

Expand all

Is September a good time to visit Keflavík?

September is typically wet for visiting Keflavík, with average highs of 10°C (50°F) and around 18 rainy days. Keflavík, Iceland in September has mild conditions, with highs averaging 10.1°C (50°F) and noticeably cooler mornings. R

Does it rain a lot in Keflavík in September?

Keflavík typically sees around 18 rainy days in September with 135 mm (5.3 in) of total rainfall. Pack a waterproof jacket.

Does it get cold at night in Keflavík in September?

Nights in Keflavík during September are cool at around 7°C (45°F). Bring a jacket or sweater for evenings.

What should I pack for Keflavík in September?

With highs of 10°C (50°F) and lows of 7°C (45°F) in September, we recommend: Layered clothing, Light jacket, Umbrella, Waterproof jacket, Waterproof shoes. Comfortable walking shoes are essential.

Is September among the best months weather-wise in Keflavík?

September is not the most favourable month weather-wise in Keflavík. Consider visiting during months with milder temperatures or less rainfall for a better experience.

What is the UV index in Keflavík in September?

The average UV index in Keflavík during September is 2 (low). No special sun protection is needed.

How many hours of daylight are there in Keflavík in September?

Keflavík gets approximately 13 hours of daylight per day in September, with around 7 hours of sunshine.

Does it snow in Keflavík in September?

Snow is uncommon in Keflavík during September based on 10-year climate averages.

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