Kupala Day is celebrated in Poland

Poland

Poland , officially the Republic of Poland , is a country in Central Europe bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian exclave, to the north...

, Russia

Russia

Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

, Belarus

Belarus

Belarus , officially the Republic of Belarus, is a landlocked country in Eastern Europe, bordered clockwise by Russia to the northeast, Ukraine to the south, Poland to the west, and Lithuania and Latvia to the northwest. Its capital is Minsk; other major cities include Brest, Grodno , Gomel ,...

 and Ukraine

Ukraine

Ukraine is a country in Eastern Europe. It has an area of 603,628 km², making it the second largest contiguous country on the European continent, after Russia...

 currently on the night of 6/7 July in the Gregorian or New Style

Old Style and New Style dates

Old Style and New Style are used in English language historical studies either to indicate that the start of the Julian year has been adjusted to start on 1 January even though documents written at the time use a different start of year ; or to indicate that a date conforms to the Julian...

 calendar, which is 23/24 June in the Julian or Old Style

Old Style and New Style dates

Old Style and New Style are used in English language historical studies either to indicate that the start of the Julian year has been adjusted to start on 1 January even though documents written at the time use a different start of year ; or to indicate that a date conforms to the Julian...

 calendar still used by many Orthodox Churches. Calendar-wise, it is opposite to the winter solstice holiday Korochun

Korochun

Korochun is a Slavic holiday, it is considered the day the Black God and other spirits associated with decay and darkness are most potent.It was celebrated by pagan Slavs on December 21 the longest night of the year and the night of the winter solstice...

. The celebration relates to the summer solstice

Summer solstice

The summer solstice occurs exactly when the axial tilt of a planet's semi-axis in a given hemisphere is most inclined towards the star that it orbits. Earth's maximum axial tilt to our star, the Sun, during a solstice is 23° 26'. Though the summer solstice is an instant in time, the term is also...

 when nights are the shortest.

Some early mythology scholars, such as Sir James Frazer, claimed that the holiday was originally Kupala

Kupala

Polish Noc Świętojańska or Sobótka Russian, Ukrainian Ніч на Купала or Купало/Купайло and Belarusian Купала may mean the traditional fest or the name of a putative god...

; a pagan

Paganism

Paganism is a blanket term, typically used to refer to non-Abrahamic, indigenous polytheistic religious traditions....

 fertility rite later accepted into the Orthodox Christian

Eastern Christianity

Eastern Christianity comprises the Christian traditions and churches that developed in the Balkans, Eastern Europe, Asia Minor, the Middle East, Northeastern Africa, India and parts of the Far East over several centuries of religious antiquity. The term is generally used in Western Christianity to...

 calendar.