https://intermin.fi/en/flag-and-arms/flag-flying-days

Finnish flag days
Finland has official flag days and national flag days designated in the calendar. The flag may be flown on other days as well.

Flying the flag is a great and dignified way to express joy and emphasise a day of celebration. Flying the flag is also a great way of showing respect or expressing sorrow. There is no reason to be shy about flying the flag. No reason is too small for flying the flag.

Finland has a rather tolerant flag flying culture, although a certain degree of sombreness is connected to flying the flag. It is good to remember that Finland is one of the best countries in the world. This is cause to rejoice, and hoisting the Finnish flag is a great way to celebrate independence.

Saturday between 20 and 26 June, Midsummer Day; the occasion is also celebrated as the Day of the Finnish Flag