The Polish Vexillological Society (Polskie Towarzystwo Weksylologiczne, PTW) was established in 1992 and has been a FIAV member since 1995. PTW’s website weksylologia.pl has a wealth of Polish-language content, including back issues of the society’s colorful newsletter, Flaga.
Here is their statement regarding Vexiday:
Polskie Towarzystwo Weksylologiczne celebrates Vexiday by inviting new members to join our association. Sign up at weksylologia.pl. We will hold a meeting and everyone sharing our interest is invited. To celebrate Vexiday we encourage you to hang out your flags from balconies to show your adoration for our joint endeavour-vexillology. Visit our website for more information.
We are happy for their support and participation!