All over the Netherlands, the public warning sirens are tested at exactly 12.00 noon on the first Monday of every month. The siren sounds for 1 minute and 26 seconds without interruption. This is a test signal so there is nothing to worry about. The sirens are never tested on a national or religious holiday or Remembrance Day, even if they fall on the first Monday in the month.Information provided by Brunssum HIVE.