Open Your Umbrella Indoors Day is observed on March 13, 2021. On this day one should open an umbrella within closed buildings, although this is supposed to bring bad luck. Whether this superstition is true or not, can therefore be tested with the Open-Your-Umbrella-Indoors-Day.
We have placed a detailed description of this event on this page: Open Your Umbrella Indoors Day 2020. For further information please stop by there!