Listen to: Valborgskören, Umeå: Sköna Maj Välkommen...

Choral singing is a popular pastime in Sweden, and one occasion when nearly every choral singer in the country lets it rip is the evening of April 30, known as Walpurgis Night or, more strictly as Walburga’s Eve (Valborgsmässoafton), being the eve of the commemoration of St. Walburga’s canonization on May 1.
Bonfires are lit, often on hilltops where they will be visible from a long way off, and when the crackling of the fire is at its height, a number of gentlemen (though nowadays as often ladies) step forward, many wearing peaked caps with a white top and some sort of emblem above the peak. They proceed to sing a number of songs, which are the same everywhere in the country and maintain that this evening marks the end of winter and the coming of spring. Rather touching if, meantime, sleet and snow are bidding fair to put the fire out, but most years, in the south of Sweden at least, spring is well into its stride.
To find a celebration in Swedish America near you, see Nordstjernan Events Calendar
Choral singing is a late and middle-class addition to the ancient practice of gathering around a fire on the evening before May Day, and probably derives from the manner in which students in Uppsala and Lund have been celebrating the arrival of spring for two centuries now.


Scaring off predators or witches...
But the bonfire goes back further than that. In Sweden and many other countries too, the lighting of bonfires one evening in spring was an ancient custom and it is a moot point among scholars whether this was done to scare off predators before the cattle and sheep were put out to graze, or whether there was some supernatural, magical purpose involved. The Germans, for example, sought through the fires to protect themselves against the witches gathering this night to worship the devil.
The Swedish custom is descended from the virulent Walpurgis fires of north Germany and since most German immigrants were to be found in Stockholm and surroundings, this is where the custom first took root. Other parts of Sweden earlier had other bonfire evenings, e..g., around Easter but the capital city always set the tone of things and so the bonfires and the singing have now fallen in line with the Stockholm way of doing things.

Saint Walburga was an English born saint who traveled as a missionary to the Frankish Empire in present day Germany in the 700s. The feast of Walburga is on February 25 in the Catholic calendar, the day of the Saint’s death in 777 or 779. In Sweden as in Finland the canonization has become the date of commemoration and the evening prior Walpurgis Night and in Germany the witches’ Sabbath.

'Första Maj' - May First
It was no coincidence when, during the 1880s, the Labor movement choose May Day for its annual manifestation. In many parts of Europe the day had been a secular festival, a kind administrative New Year’s Day in bygone society. This was the day when accounts for the year were presented and new officers were elected for the year to come. Work would be at a standstill, giving journeymen and apprentices a day off without any need for churchgoing. In Stockholm from the early 19th century onwards, May Day developed into a popular festival in Djurgården Park, complete with procession and royal visit.
As the 19th century wore on, this holiday was turned into an annual rally of industrial workers, at the same time as the employers’ organizations and authorities acquired different routines and activities.

Source: Professor Jan-Öjvind Swahn