@Green-Bean
Right there is no way to customize the color scale on the App. You have to do it on the website www.windy.com, on desktop/laptop.
On iPad it is possible if you use your browser with www.windy.com
See screenshot of my iPad with color scale settings page

I adjusted the color scale so that it shows jet streams.

@siim I'm guessing you don't have an icm color profile installed and active in your system, changing the settings alone without installing an icm color profile doesn't cause the problem.

@Korina I understand your limitations. Thank you anyway for taking the time to respond. Maybe natural development of software will end up fixing it.

Greetings