Will the down jacket fade when exposed to the sun at 30 degrees for an hour?

It will fade. Down jackets should not be dried for too long, usually for about half an hour at most. Because the down inside the down jacket is a kind of light substance, if it is exposed to the sun for a long time, it is easy to damage the down, reducing its warm-keeping function and fading. When drying down jackets at ordinary times, you must pay attention to drying them in a cool and ventilated place.