os/date should be able to handle a given timezone.

[amano-kenji]

For, example

(os/date (os/time) "America/New_York")

[zevv]

On POSIX systems this might work for you:

(os/setenv "TZ" "America/New_York")
(os/date (os/time) true)

[CosmicToast]

This is non-trivial while maintaining strict ISO C99 compatibility (or, indeed, strict ISO C-anything compatibility), as it does not specify any way of doing this. On POSIX, setting TZ is indeed the correct approach though.

[amano-kenji]

@zevv I think os/date should document TZ environment variable, then.