The sky in October seems to be bluer than at any other time of the year.
There are a few reasons for this.
The first is that humidity levels in October are usually low.
With less moisture in the air, we usually have fewer clouds and haze.
Also, lower humidity allows for less scattering of light, allowing for deeper blue colors.
Secondly, in October, the Sun’s position is lower in the sky.
This lower position means more of the sky is angled away from the Sun, decreasing the incoming levels of red and green.
This leaves more blue available to reach our eyes.
Finally, when the yellows, reds, and oranges of autumn leaves are seen against the sky, the blue will appear richer because of the contrast.
So, if you think the sky seems especially blue in October, you’re correct, and there are some valid reasons for it.