Atmospheric variables – like pollution, volcanic dust, and even moisture – can have a strong effect on sunsets.
The time of year also has an effect on how intense a sunset is likely to be.
Clouds can also produce vivid pinks, oranges and violets – especially ones that are high enough to intercept “clean” light that has not yet been touched by pollution
Stare at the sun before it happens, your eyes won’t be able to see it. Look too late, and it’s gone.