Every year on the first wednesday of february Switzerland does a test of all their alarm sirens.
Wednesday feb 3rd 2021 was again siren test day .
In the afternoon at 1.30PM all over Switzerland sirens were screaming.
here is info from the government site :
https://www.babs.admin.ch/en/alarm/test.html

So I drove to Sion airport in Valais canton and waited for 1.30PM. Was there with my dog , Golden Retriever Bella. She hardly noticed.

a second video will be available shortly with recording of the 2nd test, "water alert" , since Sion is in a valley with huge water dams that are potentially dangerous.

filmed with a Panasonic X1500 in 4K 60fps, and sound recorded with external Rode stereo microphone.