All three dimensions of color - hue, value and croma, change with changing weather and even with the changing hours of the day.
Light illuminates objects differently according to the angle at which it touches down. That affects the hue or color we see.
Shadows will appear darker when the sun is stronger, less contrasting when the light is weak. The result is a constantly changing value relationship between the elements of the composition, one of the difficulties in plein air painting and the reason most plein air painters work small.
The intensity of the color depends on the waether too, particles in the air may create duller colors or a stunning, red sunset. After a rain colors look fresher, pollution or fog will put a veil around colors, and so on.
So, watch out if someone claims to be the "painter of light", it's no more than a catchy phrase. You can't paint light, just the effects it has on the natural world.