To express (just) in case in French, you use the expression (juste) au cas où.
Look at the following examples:
J'en ai racheté, juste au cas où.
I bought some more, just in case.
Nous avons acheté de la crème solaire, au cas où.
We bought some suntan lotion, just in case.
Au cas où vous vous demanderiez où elle est, elle est allée au marché.
In case you're wondering where she is, she went to the market.
Je te le dis au cas où tu ne serais pas au courant.
I'm telling you in case you weren't aware of it.
The delicate point here is the question of the mood following au cas où. Indeed, as it expresses an uncertain state or an hypothesis, you could be tempted to use Le Subjonctif. That would be a mistake!
With the expression (juste) au cas où, you can only use Le Conditionnel.
Je te le dis au cas où tu ne le saurais pas.
I'm telling you in case you don't know.
Au cas où vous auriez faim, je vous ai fait un sandwich.
In case you get hungry, I made you a sandwich.
Learn more about these related French grammar topics
Examples and resources
Au cas où vous auriez faim, je vous ai fait un sandwich.
In case you get hungry, I made you a sandwich.
J'en ai racheté, juste au cas où.
I bought some more, just in case.
Je te le dis au cas où tu ne serais pas au courant.
I'm telling you in case you weren't aware of it.
Au cas où vous vous demanderiez où elle est, elle est allée au marché.
In case you're wondering where she is, she went to the market.
Je te le dis au cas où tu ne le saurais pas.
I'm telling you in case you don't know.
Nous avons acheté de la crème solaire, au cas où.
We bought some suntan lotion, just in case.
Q&A
Aurélie
Kwiziq language super star
9/05/17
No, you could also use "il y a du soleil", simply with "avoir" in Le Conditionnel as such:
"Anthony apporte ses lunettes de soleil au cas où il y *aurait* du soleil."
I hope that's helpful!
À bientôt !
Tom
Kwiziq community member
17/07/17
Mel
Kwiziq community member
16/02/17
Aurélie
Kwiziq language super star
12 September 2016
1 reply
David asked: "Why does "au cas où" take the conditional rather than the subjunctive?"
Aurélie
Kwiziq language super star
12/09/16
Bonjour David !
Unfortunately, I have to admit I have no explanation for you :(
I must even admit that as a native speaker, I actually used to make that mistake regularly before looking into it for the site...
All I can say is that Le Conditionnel is also a mode that expresses hypotheses and theoretical cases, hence it's logical that it'd be used in such a context.
I hope that's helpful!
Laura
Kwiziq language super star
30/08/16
Literally, it's "you would be wondering," which we'd never say in English. Both "you were wondering" and "you are wondering" are acceptable.
Pauline
Kwiziq community member
31/08/16
Barbara
Kwiziq community member
16 January 2018
1 reply
When is "jusqu'au cas où used instead of "au cas où"?
Aurélie
Kwiziq language super star
16 January 2018
16/01/18
"Jusqu'au cas où" doesn't exist at all, you're probably thinking of "juste au cas où", which is indeed an alternate option :)
Bonne journée !