I always look for driving sunglasses with a strong amber gradient; it adds an instant summer-like look no matter where you are. The same can be done with photographs.
- Click your foreground color swatch and select a nice amber orange.
- Create a new gradient layer via Layer > New Fill Layer > Gradient. Check “Reverse” or rotate it 90degrees.
- Change the blending mode of that new gradient layer to “Color” and reduce the opacity to about 40% or so.
- Instant summer.