Selfoss weather is characterized by cold temperate sub-polar oceanic climate with cool summers and cold winters where the temperature rarely drops below -10 degree Celsius. On the whole the city is warmer when compared to North Iceland throughout the year.
Summer: June to August is summer season but the weather is quite cool and the average temperature is usually between 10-13 degree Celsius. August can be called the warmest month of the year. Also minimum rainfall occurs during the summer.
Autumn: September to October is autumn. With the onslaught of the rainy season, mercury drops down a little bit to 6-10 degree Celsius and October in Selfoss is the wettest month.
Winter: November to March is the winter period with heavy snowfall, occasional rains, strong winds and the weather dropping down to -3 to 0 degree Celsius. January is the coldest month of the year.
Spring: April and May is spring season and the temperature varies from 3-6 degree Celsius. There is a considerable increase in the amount of sunshine received by the city, which makes the weather sunny and cool.
There is not a defined best time to visit Selfoss as the city has different attractions to offer to different people at different times of the year.
The summers have long days and a better weather to offer. Also one might get a glimpse of the midnight sun while visiting. There is also the ‘Summer in Selfoss’ festival which is a treat to experience. The winters though offer beautiful viewing of the Northern Lights because of the long nights. The spring and autumn months have a good but unpredictable weather and one will find Selfoss less crowded and with cheaper rates everywhere.