Saint Andrew is the patron saint of Cyprus, Scotland, Greece, Romania, Russia, Ukraine, Bulgaria, the Ecumenical Patriarchate of Constantinople,  San Andres Island, Colombia and Saint Andrew, Barbados.
St. Andrew's Day ( Scots: Saunt Andra's Day , Scottish Gaelic: Là Naomh Anndrais ) is Scotland's official national day. In 2006, the Scottish Parliament designated St Andrew's Day as an official bank holiday. It is also a national holiday in Romania (since 2015).
In Germany, the feast day is celebrated as Andreasnacht ("(St.) Andrew's Night"), in Austria with the custom of Andreasgebet ("(St.) Andrew's Prayer"), and in Poland as Andrzejki ("Andrew's (festivities)"), in Russia as Андреева ночь ("Andrew's night").
Traditions and celebrations in Scotland
The celebration of St Andrew as a national festival is thought to originate from the reign of Malcolm III (1034–1093). It was thought that ritual slaughter of animals associated with Samhain was moved to this date, so as to assure enough animals were kept alive for winter. But it is only in more recent times that the 30 November has been given national holiday status. 
In 2006, the Scottish Parliament passed the St. Andrew's Day Bank Holiday (Scotland) Act 2007,  which designated the Day as an official bank holiday. If 30 November falls on a weekend, the next Monday is a bank holiday instead. Although it is a bank holiday, banks are not required to close and employers are not required to give their employees the day off as a holiday.
The University of St Andrews traditionally gives the day for all the students as a free holiday, but this is not a binding rule.
St Andrew's Day is an official flag day in Scotland. The Scottish Government's flag-flying regulations state that the Flag of Scotland (the Saltire or Saint Andrew's Cross) shall fly on all its buildings with a flagpole.  Prior to 2002, the Scottish Government followed the UK Government's flag days and would only fly the Union Flag on St Andrew's Day. The regulations were updated to state that the Union Flag would be removed and replaced by the Saltire on buildings with only one flagpole. 
The flying of the Union Flag from Edinburgh Castle on all days, including St Andrew's Day causes anger among some Scottish National Party politicians who have argued that the Saltire should fly on 30 November instead.  However, the Union Flag is flown by the British Army at the Castle as it still is an official British Army flag flying station.
In Scotland, and many countries with Scottish connections, St Andrew's Day is marked with a celebration of Scottish culture with traditional Scottish food, music and dance. In Scotland the day is also seen as the start of a season of Scottish winter festivals encompassing St Andrew's Day, Hogmanay and Burns Night.  In Edinburgh, there is a week of celebrations, concentrating on musical entertainment and traditional ceilidh dancing. A ceilidh is a social event with couples dancing in circles or sets (groups of six or eight people). In Glasgow city centre, a large shindig, or party, with traditional music and a ceilidh are held. In Dumfries, songs are performed in the Burn's night tradition.
Saint Andrew's Day is celebrated as the national day of Independence in Barbados. As the patron saint, Saint Andrew is celebrated in a number of Barbadian symbols including the cross formation of the Barbadian Coat of Arms, and the country's national honours system which styles persons as Knights or Dames of St. Andrew. 
There are a few pre-Christian Romanian traditions connected to St. Andrew's Day, some of them having their origin in the Roman celebrations of Saturn.   The Dacian New Year took place from 14 November until 7 December; this was considered the interval when time began its course.  One of the elements that came from the Roman and Thracian celebrations concerned wolves. During this night, wolves are allowed to eat all the animals they want. It is said that they can speak, too, but anyone that hears them will soon die. Early on St. Andrew’s day, the mothers go into the garden and gather tree branches, especially from apple, pear and cherry trees, and also rosebush branches. They make a bunch of branches for each family member. The one whose bunch blooms by New Year's Day will be lucky and healthy the next year.
The best known tradition connected to this night concerns matrimony and premonitory dreams. Single girls must put under their pillow a branch of sweet basil. If someone takes the plants in their dreams, that means the girl will marry soon. They can also plant wheat in a dish and water it until New Year’s Day. The nicer the wheat looks that day, the better the year to come.
St. Andrew's Eve
In parts of Ukraine, Germany, Austria, Slovakia, Poland, Russia and Romania, a superstitious belief exists that the night before St. Andrew's Day is especially suitable for magic that reveals a young woman's future husband or that binds a future husband to her. Many related customs exist: for example, the pouring of hot lead into water (in Poland, one usually pours hot wax from a candle through a key hole into cold water),  divining the future husband's profession from the shape of the resulting piece (related divinations using molten metals are still popular in Germany on New Year's Eve).
In some parts of the Czech Republic, Hungary and Slovakia young women would write down the names of potential husbands on little pieces of paper and stick these into little pieces of dough, called halušky. When cooked, the first one to float to the surface of the water would reveal the name of their future husband.
In Poland, the holiday Andrzejki is celebrated on the night of the 29th through 30 November. Traditionally, the holiday was only observed by young single girls, though today both young men and women join the party to see their futures.  Some women put pieces of paper (on which they have written potential husbands) under the pillow and first thing in the morning they take one out, which according to tradition reveals their future husband.
In Romania, it is customary for young women to put 41 grains of wheat beneath their pillow before they go to sleep, and if they dream that someone is coming to steal their grains that means that they are going to get married next year. Also in some other parts of the country the young women light a candle from the Easter and bring it, at midnight, to a fountain. They ask St. Andrew to let them glimpse their future husband. St Andrew is invoked to ward off wolves, who are thought to be able to eat any animal they want on this night, and to speak to humans. A human hearing a wolf speak to him will die.  St. Andrew is also the patron saint of Romania and the Romanian Orthodox Church.