Autism and not wanting to wear clothes

This is very common and may well be a sensory issue. Or perhaps a transition issue in that he doesn't understand needing to get dressed. 

You could try using symbols to help him understand the need to get dressed. It may be as simple as an image of his school paired with his school uniform helps him understand he needs to get dressed for school. Or a visual schedule of the steps of getting dressed, possibly paired with something he would prefer afterwards. Now and next can also be helpful now dressed next breakfast or possibly now dressed next "preferred activity".

If it is a sensory issue it can be a bit trickier. Does your son wear pyjamas to bed? If so do you have the same issue getting him to undress? Does he take his clothes off again at the first opportunity or once dressed is he ok? Does he resist any an all clothes or are there some that he prefers? The answers to the questions can help you break down whether it's a specific sensory issue or a dislike of having clothes on (or that it isn't a sensory issue at all it is more an issue of understanding/transition as above). If he is ok with some textures then I would try to find more of these so that he feels more comfortable and is less adverse to getting dressed.

Good luck.

This is very common and may well be a sensory issue. Or perhaps a transition issue in that he doesn't understand needing to get dressed. 

You could try using symbols to help him understand the need to get dressed. It may be as simple as an image of his school paired with his school uniform helps him understand he needs to get dressed for school. Or a visual schedule of the steps of getting dressed, possibly paired with something he would prefer afterwards. Now and next can also be helpful now dressed next breakfast or possibly now dressed next "preferred activity".

If it is a sensory issue it can be a bit trickier. Does your son wear pyjamas to bed? If so do you have the same issue getting him to undress? Does he take his clothes off again at the first opportunity or once dressed is he ok? Does he resist any an all clothes or are there some that he prefers? The answers to the questions can help you break down whether it's a specific sensory issue or a dislike of having clothes on (or that it isn't a sensory issue at all it is more an issue of understanding/transition as above). If he is ok with some textures then I would try to find more of these so that he feels more comfortable and is less adverse to getting dressed.

Good luck.