[roel_v]

OK, it might be a social construct. I'd never say 'treize heures' to set a time with my Parisian colleagues, and neither would they (to the best of my recollection). Sometimes people would say it, yes, but it'd sound strangely artificial, like read literally from a schedule - which in many cases it would be.

[mgbmtl]

In Quebec, 24 hour time has changed from being a nerd thing, to being the standard way of saying time. That's how the media pronounces time, how people write it down, etc. As others have mentioned, cell phones probably have something to do with that too.

[mattkrause]

This sometimes gets "localized" too, so you see " - Le film commence à vingt-deux heures trente. - The film begins at 10:30 pm. " on a bilingual sign.

Google Translate sometimes seems to know how to do this too.

[jobigoud]

> I'd never say 'treize heures'

One of the main midday newscast is called "Le journal de treize heures".

[ekianjo]

And the 8pm one is called le vingt heures. Really used everywhere.

[wott]

I have the feeling that it is fairly recent. When I was a kid, I think that nobody used it regularly, then it started to be used on the radio and TV, and then, when I came back home after having spent 8 years abroad, I was surprised to hear it used by the average citizen.

I am not fond of it. It is heavy and in most use cases, doesn't bring more information than 1-12, because the context makes generally obvious to know if we're talking about AM or PM.

[roel_v]

Okay okay I get it - you're all gently breaking it to me that I'm now officially old. I, too, used to be with it, but then they changed what it was. Now what I'm with isn't it, and what's it seems weird and scary to me, and it'll happen to you, too.

(sorry about that ;) )