I took this in Swakopmund, Namibia in 1999. Believe it or not, I did not use photoshop to exaggerate the colors. This is what it actually looked like (minus the excessive contrast that sometimes results from scanning slides).
Perhaps the effect is due to all the dust in the air over there. Or maybe the fact that this occurred on one of the handful of days when Swakopmund received a little rainfall had something to do with it. I never thought to ask whether this was a normal phenomenon or not. It could very well be, since Africa is known for its sunsets.