The image below was not white balanced properly and is therefore too blue. Since we are only working with the jpg file we do not have the ability to white balance the image. We will have to color correct it manually. Instead of using the curves or color balance adjustment you can use the Variations settign within Photoshop.
Within Photoshop go to Image/Adjustments/Variations
You will see that you know have variations of colors applied to the picture set up like a color wheel. Since we know our original image had too much blue. Pick the two colors opposite blue and cyan (Yellow and Red) and apply them.
You will notice the changes applied to your image.
However you will notice that it’s now a bit too read. Add a Layer Mask by clicking the Layer Mask button on your Layers Window.
Make sure that your foreground color is black.
Using your paintbrush, paint black on the mask on the areas where the sky is. This way you mask out the sky and do not apply the Yellow and Red variation allowing the blue to come through.
If at any time you want to see the mask that you are creating. Go to Window/Channel and open your channels. There you will see your mask as its own channel. Toggle the mask on by clicking on the EYE icon and you will see it represented on your image in transparent red. When you dont want to see it, toggle it off.
Below is the final output after the variations and masking out the sky.