Why does Minnesota test tornado sirens on the first Wednesday of the month? The local custom recently startled a New York-based cable news anchor on live television. April 30, 2021 — 8:20am Related coverage The wail of sirens in the distance means one thing to most Minnesotans: It must be Wednesday. Testing tornado sirens at 1 p.m. on the first Wednesday of the month is a local tradition. But reader Andrew Engen wanted to know the origins of this cacophonous custom, which recently startled a New York-based cable news anchor on live television. File photo A siren installed atop a fire department building in Southeast Minneapolis is tested in January 1952.