Ours are tested on the first Wednesday of every month at noon in clear weather. But here they're not just nuke sirens, they're warning sirens that are used pretty frequently in the springtime because I live in the Dallas area, which is part of Tornado Alley. That's why they only test them when it's not cloudy or overcast. We have so many storms in the springtime here that when I hear the siren-testing, I immediately think of tornados instead of nuclear danger.