Wikipedia: “Constitution Day is the national day of Norway and is an official public holiday observed on 17 May each year. Among Norwegians, the day is referred to simply as syttende mai ("Seventeenth May"), Nasjonaldagen ("National Day") or Grunnlovsdagen ("Constitution Day"), although the latter is less frequent.”
The Covid-19 restrictions have stopped almost all celebrations across the entire country. It doesn’t stop people to fly the flag though. It’s a wet and miserable day, so I would stay at home anyway.