Replace a sky using Photoshop
You can rescue a bland or overexposed sky by replacing it with a better version using Photoshop!
Fixing a bland or blown out sky is relatively easy in Photoshop. All that’s required is an image with a better sky that you can merge into the main photo!
Open up your images in Photoshop, and start by adjusting the Curves in your main photo. This will improve the definition along the horizon and make your blending easier, which may be a little hazy if you have an overexposed sky.
With both your photos open in Photoshop, make a selection of an area of sky that you wish to drag across to your main photo.
Drag the sky into your main image and press Cmd/Ctrl+T to activate Free Transform and resize the sky to fit.
At the base of the Layers palette, add a layer mask and then use the Brush Tool to blend your new sky into the photo.