In the calendar of the ancient Celts it is easy to understand the importance of the first day of summer. The ‘fire of Bel’, or Beltane as it was called, was celebrated with bonfires to welcome the new season. Known today as May Day, it has through the ages remained the most important day of the folklore year. 
May is the 5th month of the year. Traditions of festivals and doing special things have continued till the present day. The Romans also held a festival in honour of a Goddess they called, "Flora" who looked after flowers. 
Communists and Social Democrats frequently hold rallies on or round the 1st of May and May Day is a public holiday in many Countries. Although events which led to the celebration of an international "Labor Day" actually took place in Chicago in 1886 (Haymarket Riots). The US celebrates Labor Day at a different time to avoid the appearance of solidarity with other international labor movements.
Seasons and weather
- In the Northern Hemisphere May is well into spring, the weather is getting warmer, trees and other plants are starting to grow or growing well. People know it will soon be summer.
- In the Southern Hemisphere, May is late autumn, the weather is getting steadily colder.