What does this siren mean? It repeats and I can't sleep!?

Question

I live in Texas and I keep hearing this repeating siren. It's an "ooo" (oo as in boo) and it slowly gets louder. The actual oo doesn't last very long, but it repeats. Sometimes it sounds like it's far away and sometimes it sounds close. We just moved here and I've never heard it before.

I know it's not a tornado siren but it's kind of annoying (the weather is clear). And I'm a little worried because it keeps going off and I don't know what it means. I suppose they are just testing the sirens..but still =P

Thanks!

Answer 1

It could be testing of bad weather alarms.  It could also be a notification in a manufacturing plant.  The reason you don't hear it with the same volume is due to weather itself.  This will cause the pitch to change, or the volume to change.  I wouldn't worry about it.

Answer 2

fog horn? im not sure..