Thanks for that, haven’t heard them before as I’m not usually in a large towns, but I will be today and you’ve saved me some additional laundry.
Yes we hear them first Wednesday of the month, bit un nerving at first.
We hear them every week day 12 noon. There are two in town which have slightly differing views as to exactly when 12 noon is. Time to clock off and go home for lunch. So nothing unusual for us.
We also hear the sirens when the Garonne is about to flood - very important for those affected. There are different sequences depending on how high the Garonne is flooding. Fortunately we are out of town half way up a hill, so have never troubled to learn what the different sequences mean.
Every Sunday noon for us. It is 4 kms away with trees in between, so we only hear it here when the wind is favourable (N). 
Er… David, those are church bells surely?
No, the testing of the siren on the Pompiers’ roof.
Never heard one in all the years being here 
If anything happens we are on our own here 
haven’t heard one recently - we used to get them every month. Mind you, I am now a LOT deafer than I was a coupleof years back 
How interesting. I assumed there was nothing special about our local town and that sirens were sounded at 12 noon every working day throughout France. How else do people working in the fields know it’s time for lunch? 
A watch 
Likewise.
In the countryside where I live, folk really do follow the Bells… and when the Angelus sounds… clanging like mad… folk know it’s time to get-up/go to work (around 7am)… time for lunch (around midday)… time to go home (around 7pm)
Over the years, the Bells have been out of action only a few times, but when it does happen it really can throw one’s lifestyle into turmoil… 
Seems that according to the area/location and the hazards thereabouts… many sirens are tested regularly, just in case there is a “gas leak/other awful local happening”…
But the nationwide annual testing of Sirens on 2 March is to ensure that should there be a nationwide Alert/Danger… the Sirens will do their job of alerting everyone…
and this year… I think most of us are already on high-alert and it won’t take much to make some poor soul think that we (France) are being attacked…
Hence today’s warning…
(incidentally, we’ve heard a siren sounding when it’s been lunchtime for the factory… that’s over in Charente but I’m sure it happens elsewhere… made us wonder what was going on… first time we sped by.)
Reminds me of an old joke:
A hiker rambling through the countryside encounters a farmer milking his cow in his field. As his watch has stopped, he asks the farmer if he knows the time.
The farmer pauses for a second, adjusts the position of the cow’s udder and declares “aye, it’s ten past one”.
“Crikey” say the rambler, “you can tell the time from the cow’s udder?”
“Nah,” says the farmer, but if I move t’udder, I can see Church clock across t’field" 
Ditto 
Oh dear, the wind must have been coming from the Sahara here then, never heard a thing yesterday. 
I’ll have to rely on SF to be warned that the Russians are coming.
I asked our friend who has lived here for 24 years and I got the are you stupid look and was asked what siren
We certainly don’t hear any sirens in our village… perhaps in the large towns (where there are Police and Pompiers ).
On occasions I’ve been asked to ring the church bells… to mark something extra-special… which is fine…
except that some folk will always phone me, in a panic, to find out a) who’s died… b) are we at war…
Nowadays… they might well have reason to panic… sadly.
Panic here used to be defined by 2 fast jets chasing each other across the rooftops, but now we just go with the flow.
They won’t get us, I’ve got my air rifle up in the shed. Never used in 30 odd years since I bought it to deter petrol thieves outside our flat near Nottingham. The idea was that, looking down to where the car was parked in the road, I could bounce a slug off the roof to send them packing. Somebody must have told them, after cutting the fuel line of one car and briefly stealing another, they never tried again.