add this
jQuery(document).ready(function() {
$("html").css({
'background-image': ''
});
$("html").animate({ background:'url(image.png)'},350);
});
That’s only for the first image fade effect. If you want this effect for different images you might want to try this plug-in I’m sure you will get cool output from it.
3
solved Fading a background with jQuery [duplicate]