For the freelancers: do you tell your clients you are working in another country? If so, how do you broach the topic?

I'm a freelance graphic designer and have about three solid clients that I work with. I am planning on working from Europe this summer and I'm debating if I should tell my clients I'm working from Europe or just plan to work mostly during the 9-5 hours in US (~3-11 ish in Europe). I don't want to be disrespectfully sneaky, but I'm also debating if they really need to know.

Have you discussed this with your clients? How did it go? Or did you follow a don't ask, don't tell policy? Thanks for any insight!