September weather forecast
Selfoss, Iceland

September

Weather in September

September marks the onset of autumn in Selfoss with temperatures starting to decrease and moving closer to 10°C (50°F). Rainfall increases from August's 77mm (3.03") to 95mm (3.74"), indicating the transition towards the rainy season. This month also brings along an increase in wind speed, adding a chill factor especially in the evenings. Despite these changes, daylight hours remain fairly substantial providing ample opportunities to explore the city in day time. Depending on weather preferences, visitors may find this transitionary period a unique time to visit.

Temperature

September signals a slight drop in average high-temperature, sliding from August's refreshing 13.1°C (55.6°F) to a cool 10°C (50°F). In Selfoss, the month of September records an average minimum temperature of 6.1°C (43°F), a slight dip from the daily highs.

Humidity

The months with the highest humidity are January and September, with an average relative humidity of 82%.

Rainfall

In September, the rain falls for 18.7 days. Throughout September, 95mm (3.74") of precipitation is accumulated. Throughout the year, there are 208.7 rainfall days, and 1105mm (43.5") of precipitation is accumulated.

Snowfall

June through September are months without snowfall.

Daylight

The average length of the day in September is 13h and 0min.
On the first day of September, sunrise is at 06:09 and sunset at 20:38. On the last day of the month, sunrise is at 07:31 and sunset at 18:55 GMT.

Sunshine

In Selfoss, the average sunshine in September is 4.6h.

UV index

In September, the average daily maximum UV index is 2. A UV Index value of 2, and less, symbolizes a minimal health hazard from unsafe exposure to UV radiation for the ordinary person.
Note: In September, the maximum UV index of 2 translates into these guidelines:
Most individuals face no major issues with lengthy exposure to the sun, but children, infants, and individuals with fair skin always require protection. Avoiding direct sun during mid-day hours can prevent harmful UV radiation exposure. Prioritize a wide-brim hat for comprehensive sun defense for your face, neck, eyes, and ears.

Frequently asked questions

What are the temperatures in September?
The high-temperature, in September, in Selfoss, records 10°C (50°F), while the low-temperature is 6.1°C (43°F).
What are the most humid months?
January and September, with an average relative humidity of 82%, are most humid months.
What is the average humidity in September?
In Selfoss, the average relative humidity in September is 82%.
How many days does it rain in September?
In Selfoss, in September, during 18.7 rainfall days, 95mm (3.74") of precipitation is typically accumulated.
When it does not snow?
June through September are months without snowfall.
Does it snow in September?
In Selfoss, in September, it doesn't snow. In October, it regularly snows.
How many hours of daylight does Selfoss have in September?
The average day length in September is 13h and 0min.
When is the sunrise / sunset in September?
In September, on the first day of the month, sunrise is at 06:09 and sunset at 20:38. On the last day of the month, sunrise is at 07:31 and sunset at 18:55 GMT.
How long on average sun shines in September?
In Selfoss, the average sunshine duration in September is 4.6h.
How high is the UV index in September?
In September, the average daily maximum UV index is 2. A UV Index value of 2, and less, symbolizes a low health risk from unsafe exposure to Sun's UV rays.
Average high temperature
Average low temperature
Average wind speed
Average max. wind speed
Average wind speed gusts
Average humidity
Average rainfall
Average rainfall days
Average snowfall
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility
Average temperature in September - Selfoss, Iceland
Average temperature in September
Selfoss, Iceland
  • Average high temperature in September: 10°C

The warmest month (with the highest average high temperature) is July (13.8°C).
The month with the lowest average high temperature is December (1.5°C).

  • Average low temperature in September: 6.1°C

The month with the highest average low temperature is July (8.9°C).
The coldest month (with the lowest average low temperature) is December (-1.9°C).

Average pressure in September - Selfoss, Iceland
Average pressure in September
Selfoss, Iceland
  • Average pressure in September: 1003mbar

The month with the highest atmospheric pressure is June (1013.8mbar).
The month with the lowest atmospheric pressure is January (996.8mbar).

Average wind speed in September - Selfoss, Iceland
Average wind speed in September
Selfoss, Iceland
  • Average wind speed in September: 19.8km/h

The windiest month (with the highest average wind speed) is February (24.8km/h).
The calmest month (with the lowest average wind speed) is July (14.7km/h).

Average humidity in September - Selfoss, Iceland
Average humidity in September
Selfoss, Iceland
  • Average humidity in September: 82%

The months with the highest relative humidity are January and September (82%).
The month with the lowest relative humidity is May (74%).

Average rainfall in September - Selfoss, Iceland
Average rainfall in September
Selfoss, Iceland
  • Average rainfall in September: 95mm

The wettest month (with the highest rainfall) is January (142mm).
The driest month (with the least rainfall) is June (45mm).

Average rainfall days in September - Selfoss, Iceland
Average rainfall days in September
Selfoss, Iceland
  • Average rainfall days in September: 18.7 days

The month with the highest number of rainy days is April (19.9 days).
The month with the least rainy days is December (14.3 days).

Average snowfall in September - Selfoss, Iceland
Average snowfall in September
Selfoss, Iceland
  • Average snowfall in September: 0mm

The month with the highest snowfall is March (220mm).
The months with the least snowfall are June, July, August and September (0mm).

Average snowfall days in September - Selfoss, Iceland
Average snowfall days in September
Selfoss, Iceland
  • Average snowfall days in September: 0 days

The month with the highest number of snowfall days is March (13.3 days).
The months with the least snowfall days are July, August and September (0 days).

Average daylight in September / Average sunshine in September - Selfoss, Iceland
Average daylight in September /
Average sunshine in September
Selfoss, Iceland
  • Average daylight in September: 13h and 0min

The month with the longest days is June (Average daylight: 20h and 42min).
The month with the shortest days is December (Average daylight: 4h and 30min).

  • Average sunshine in September: 4h and 4min

The month with the most sunshine is August (Average sunshine: 7h and 48min).
The month with the least sunshine is January (Average sunshine: 2h and 24min).

Average sunshine days in September - Selfoss, Iceland
Average sunshine days in September
Selfoss, Iceland
  • Average sunshine days in September: 9.7 days

The month with the most sunshine days is June (12.3 days).
The month with the least sunshine days is January (5.5 days).

Average UV index in September - Selfoss, Iceland
Average UV index in September
Selfoss, Iceland
  • Average UV index in September: 2

The month with the highest UV index is July (UV index 4).
The month with the lowest UV index is November (UV index 1).

Average cloud cover in September - Selfoss, Iceland
Average cloud cover in September
Selfoss, Iceland
  • Average cloud cover in September: 64

The month with the most cloud cover is March (Cloud cover 67).
The months with the least cloud cover are May and August (Cloud cover 59).

Average visibility in September - Selfoss, Iceland
Average visibility in September
Selfoss, Iceland
  • Average visibility in September: 9km

The month with the highest visibility is June (10km).
The months with the lowest visibility are January, February and March (8km).

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