The claim matches well-established scientific explanation and ordinary observation. Multiple authoritative sources explain that atmospheric Rayleigh scattering makes the daytime sky appear predominantly blue to human eyes. Technical nuances about violet light, perception, or “bluish white” descriptions do not change the practical truth of the statement.
Caveats
The claim describes the sky’s usual daytime appearance; it is not blue under all conditions, such as at sunset, sunrise, or heavy overcast.
A physically exact description can be more nuanced than everyday language, since scattered light is not a perfectly pure spectral blue.
Violet light is scattered even more than blue, but human vision and atmospheric absorption make the sky appear blue rather than violet.