Will any outdoor civil‑protection siren sound in Germany on September 10?

Warum: - Premise (BBK press release, 2026-09-03): On 10 September 2026 the Bundesweiter Warntag would be conducted, with the BBK sending a test at 11:00 and many municipalities additionally testing their own warning systems such as sirens. Source: bbk.bund.de/…/pm-03-warntag-ankuendigung.html → This establishes that siren activations are part of the Warntag and scheduled for 11:00. - Premise (Tagesschau, 2026-09-10 13:12): Reporting on today’s event states, “Sirenen heulten, Mobiltelefone schrillten, Digitalradios schalteten sich von selbst ein – zum sechsten Mal hat heute der bundesweite Warntag stattgefunden,” and explains it was “heute ab 11 Uhr.” Source: tagesschau.de/…/warntag-faq-100.html → This confirms that on 10 September 2026, as part of the Warntag, sirens did sound in Germany starting at 11:00. - Inference: 11:00 lies within the question’s window (10:55–11:05 CEST). “Sirenen heulten” describes audible siren signals; therefore at least one audible outdoor civil‑protection siren sounded somewhere in Germany during that window as part of the Warntag test. - Conclusion: YES.