There are ten Norwegian public holidays1 in Norway. There's a day each for Ascension and Pentecost, and three days off at Easter (these five holiday days always occur on the same weekday) plus five linked to dates that might occur on Sundays or be nulled out by the one of the five others2.
For some reason there are a lots in May and none between Pentecost and Constitution Day3 and Christmas. Their origin and purpose are as follows:
New Year's Day
1 January is a very necessary holiday. It originally simply marked the start of the new year, but it is now a day for nursing hangovers and cleaning up firework rubbish, without which no New Year celebration is complete.
It is also a good day for breaking all your New Year's resolutions.
Unlike most other countries, Norway takes Thursday through to the following Monday off for Easter, and with many Norwegians having vacation days to spare, Easter ranges from a five-day to a ten-day holiday. This is traditionally spent enjoying the last of the year's snow, even if you have to head to the mountains to find it. The Norwegian on an Easter vacation will read crime novels, eat oranges and chocolate, and eagerly await Inspector Morse or a Hercule Poirot mystery on TV.
May Day or Første mai, is the first of Norway's days off in May (obviously, since it falls on 1 May). It is also one of the days that is in danger of falling on the weekend, rendering itself useless to anyone not interested in marching in the May Day parade.
On 17 May, 1814, Norway got its Consititution. This is celebrated each year on Syttende mai with parades of children, waving flags, games for children (and parents), preceded and followed by as much ice-cream, soda and hot dogs as their bodies can hold. Those who are too old to play and too young to sit by and enjoy watching children at play, nurse their hangovers from having spent the previous evening drinking.
Like May Day, 17 May can potentially fall on the weekend, or on Ascension Day.
According to Christian teachings, Christ ascended into heaven 40 days after Easter. As Kristi Himmelfart is always on a Thursday, many Norwegians make this a four day weekend.
The Holy Ghost is supposed to have visited the disciples on Pentecost Sunday, ten days after Ascension Day. Pentecost Monday is, for some reason, also a holiday in Norway, giving a three-day weekend either late in May or in early June.
After Penecost there are no more public holidays in Norway until Christmas. Norwegians open their presents on Christmas Eve and often have half that day off work, which can also be necessary if preparing Christmas dinner. The first and second days of Christmas are public holidays.
Dealing With Norwegian Companies in Summer
Although the public holidays are usually all in May there is still one other time of the year when it is difficult to conduct business in Norway. July and early August sees a 'Common Holiday' in Norway. Although people are not bound by this, many people choose to take the same three weeks of summer off4. Trying to get hold of the people you need to at this time is a tortuous experience. Either the person you want to speak to is on holiday or someone will be unable to give you information you require because the person they need to ask is on holiday. The best approach is to not plan anything important for July or August, get it sorted before July or exercise your managerial power and force people to stay at work.