Weather in September
September in
Seltjarnarnes embodies the onset of fall, a noticeable contrast to the summer warmth of
August. The average sea temperature starts to retreat to a cooler 9.7°C (49.5°F) indicating the arrival of the fairly milder months. Length of daylight noticeably diminishes from August, reflecting the typical autumn--a shift as September progresses. Even though September ushers in a coolness signaling the start of fall,
October's weather magnifies this change.
Sea temperature
In Seltjarnarnes, the average seawater temperature in September is 9.7°C (49.5°F).
Note: In 9.7°C (49.5°F), cold shock and rapid breathing can occur when swimming at temperatures below 10°C (50°F).
Daylight
The average length of the day in September is 13h and 1min.
On the first day of the month, sunrise is at 06:12 and sunset at 20:43. On the last day of September, in Seltjarnarnes, sunrise is at 07:35 and sunset at 18:59 GMT.