On August 8, many Muslims will celebrate Eid al-Fitr, the feast marking the end of the monthlong Ramadan fast.
Ramadan, which is based on lunar cycles rather than the international calendar, can occur at any time of the year.
This year, the Islamic holy month coincided with the longest days of summer in the Northern Hemisphere for the first time since the 1980s.
For fasting Muslims that has meant especially long, hot days with no food or water between dawn and dusk.
The holiday presents a particular challenge in the northern countries of Scandinavia, where summertime means nearly full-time daylight.
The Finnish capital, Helsinki, at 60 degrees latitude, is one of the world's northernmost cities, with the summertime sun setting as late as 10:30 p.m. and rising just a few hours later.
Ramil Bilyaev, an ethnic Tatar imam who has lived in Helsinki for the past nine years, says the long days mean local Muslims have as little as three or four hours at night to eat and drink.
"This year, we agreed within the community that everyone would try to fast from the very first day," Bilyaev says. "If 20 hours without water and food was too long for someone, he was supposed to try one more day. After that, he could decide to stop fasting and fast later instead, during the winter months. We also suggested that people could fast according to the time in Saudi Arabia. Iftar, the evening meal, is between 7 and 7:30 p.m. in Saudi Arabia. Here in Helsinki, it's between 10 and 10:30 p.m. Those three hours can make a huge difference for some Muslims."
In 1986, the last time Ramadan fell so close to the summer solstice, there were relatively few Muslims living in Scandinavia.
But now there are believed to be at least 60,000 Muslims living in Finland alone, including Turks, Arabs, Tatars, and Bosniaks.
The northern location has some advantages -- for example, comparatively comfortable summertime weather for those going without water.
Daytime temperatures in Helsinki hover around 24 degrees Celsius -- considerably cooler than the 38 degrees Celsius seen currently in Mecca.
Long summertime days also mean long wintertime nights -- meaning no fear of hunger pangs the next time Ramadan falls near the winter solstice in the Northern Hemisphere, around the year 2030.
Some Scandinavian Muslims, however, say they stick to the Saudi Arabian timetable every year in order to avoid such extreme fluctuations.
But Bilyaev, who was born in Russia's Nizhny Novgorod region, says others rise to the latitudinal challenges -- even in the northernmost reaches of Finland, where the summertime days can last a full 23 hours.
"In some northern towns in Finland, where the nights are even shorter -- just one hour -- Muslims schedule their fasting according to the time of the nearest southern state and take a two to three hour break from fasting," he says. "As for myself, this is my first experience with fasting for 20 hours. I thought it would be hard, but with Allah's will, we've accomplished it. It was easier than I expected."
Written in Prague by Daisy Sindelar based on reporting by Landysh Kharrasova of RFE/RL's Tatar-Bashkir Service; Alsu Kurmasheva also contributed to this report