Test day: first Wednesday in February
Every year, on the first Wednesday in February, all sirens across Switzerland are tested. The aim is to ascertain the operational readiness of both the "General Alarm" and the "Water Alarm" sirens. The population is notified beforehand through announcements on the radio, on TV (see below) and in the press. The general public is not required to adopt a particular behaviour or take protective measures, but simply asked in advance for their understanding of the inconvenience caused by the noise of the sirens.
Two alarm signals
At 1.30 p.m. the "General Alarm" signal is sounded across Switzerland. This is a regular ascending and descending tone, which lasts for one minute, and is repeated once after a two-minute interval. Where necessary, the sirens can continue to be tested until 2 p.m.. From 2.15 p.m. to 3 p.m. (at the latest), the "Water Alarm" signal is tested in those areas that are in the proximity of dams. It consists of twelve low continuous tones lasting twenty seconds and repeated at ten-second intervals. The operational readiness of a total of 7,800 sirens is tested.