The length of daylight hours varies greatly around the world and depends on the time of year. The country with the longest day experiences continuous daylight for a 24-hour period at least once a year. This phenomenon is known as the midnight sun and occurs inside the polar circles in the summer months. Here we take a look at which countries have the longest days and why.
What Causes the Longest Days?
The tilt of the Earth on its axis and the Earth’s revolution around the sun cause seasons and variations in daylight hours throughout the year. At the summer solstice, around June 21 in the Northern Hemisphere, the North Pole is tilted most directly towards the sun. This means the sun does not set below the horizon inside the Arctic Circle, resulting in 24 hours of daylight. The further north you go inside the polar circle, the more days of midnight sun occur around the summer solstice. A similar phenomenon happens inside the Antarctic Circle in the Southern Hemisphere around December 21.
Countries with the Longest Days
The countries with the longest daylight hours are those that extent furthest north inside the Arctic Circle. These include:
- Greenland – Greenland has the world’s longest day, with continuous sunlight for around 4 months in summer at its northernmost point.
- Norway – The northernmost parts of mainland Norway experience midnight sun in summer, with 24 daylight hours for up to 2 months.
- Sweden – The northern regions of Sweden inside the Arctic Circle have up to 20 hours of daylight per day in June.
- Finland – Northern Finland has up to 73 days of midnight sun per year.
- Russia – Russia has the world’s largest zone of continuous daylight inside the polar circle, up to 24 hours per day for around 100 days.
- Canada – The northernmost regions of Canada like Nunavut have continuous daylight from May to August.
- Alaska (USA) – Alaska experiences up to 24 hours of daylight for around 60 days in summer.
Iceland and Denmark also have very long days in summer, though slightly less than the countries inside the polar circle. The further south you go, the shorter the daylight hours around the summer solstice. However, all countries do experience a period of continuous daylight and darkness each year.
Longest Day by City
Looking at individual cities, the longest day occurs in:
| City | Country | Longest Daylight Hours |
|---|---|---|
| Nuuk | Greenland | 24 hours |
| Tromso | Norway | 24 hours |
| Rovaniemi | Finland | 24 hours |
| Reykjavik | Iceland | 21 hours 45 minutes |
These cities are located far north inside the Arctic Circle and have at least one day per year with 24 hours of daylight. Many other northern cities just outside the polar circle also have extremely long days in June.
Why Does it Happen?
The midnight sun occurs because of the 23.5 degree tilt of the Earth’s axis of rotation relative to its orbit around the sun. This tilt means that during the northern summer solstice, the North Pole points directly towards the sun while places with lower latitude are tilted at an angle away. Inside the Arctic Circle, the sun does not set below the horizon at this time of year, so there is continuous daylight. The opposite happens in winter when the pole tilts away from the sun causing polar night.
Human Impacts of Long Days
The long daylight hours in Arctic regions have many impacts for people living there and on the environment:
- Disruption of sleep cycles and circadian rhythms due to constant daylight
- Increased economic activity with longer working hours
- Effects on wildlife migration patterns and feeding cycles
- Increased plant growth due to longer photosynthesis time
- Melting of sea ice and glaciers due to greater sun exposure
Some people use blackout curtains to block out the constant daylight in summer. The midnight sun also creates unique landscapes and sights not visible elsewhere, attracting tourists to Lapland regions.
Longest Day Festivals
The summer solstice is celebrated in many northern communities and countries. Some examples of festivals include:
- Midsummer Festival, Sweden
- Juhannus, Finland
- Secret Solstice, Iceland
- Midnight Sun Marathon, Norway
- National Aboriginal Day, Canada
These festivals celebrate the longest day and often feature music, food, bonfires and revelry throughout the night. The contrasts of long days and nights are Integral to northern culture.
Conclusion
Inside the Arctic Circle, the summer solstice brings a period of continuous daylight with 24 hours of sun per day. Greenland has the world’s longest day near its northernmost point, while other countries like Norway, Sweden, Finland and Russia also experience midnight sun inside the polar circle due to their high latitudes. The tilt of the Earth and position relative to the sun create these extreme variations in daylight hours throughout the year at northern latitudes. While the long days have many impacts, they are also celebrated through cultural festivals and create some breathtaking scenery.