When writing these things, I prefer using the “sleep” command as the while condition. This way, the loop is easier to break out of. I.e. when I press Ctrl-C, the sleep command returns a non-zero exit code, and the while loop terminates gracefully:
while sleep 60; do clear; curl -s wttr.in; done
Otherwise, I very often get a loop which stubbornly refuses to abort, and I have to hammer both Ctrl-C and Ctrl-\ to make it stop. The downside is, of course, that I have to wait 60 seconds (in this case) the first time. When this is a problem, I just unroll the loop slightly and add an extra invocation to the beginning:
clear; curl -s wttr.in; while sleep 60; do clear; curl -s wttr.in; done
This could be generalized into a terminal watch function:
termwatch(){ delay="$1"; shift; clear; "$@"; while sleep "$delay"; do clear; "$@"; done; }
termwatch 60 curl -s wttr.in
> ^C breaks out of this loop just fine on my system.
It might be different when run as a script (with a separate shell process) to when run as an explicit loop in an interactive shell, or a shell function.
You can try to run it with any command that has ANSI output, and you will see it.
As a simple alternative, you write your own 'watch' like this:
while true; do curl -s wttr.in; sleep 60; clear; done