I’m thinking of getting/making two outdoor enclosures for my male panther chameleons. I have lots of questions though. I live in NY so this would obviously only be for summer. What are the temps I need to look out for to put them out in the enclosure?
Pretty much the same as for indoors, though nighttime temp can go as low as 55F (lower than that could cause issues).
During the night ideal temperatures should remain between 60-70°F, avoiding any temperatures below 55°F due to risk of causing digestive issues and other illnesses.
https://researchpet.com/care-guides/panther-chameleon
I do plan on bringing the out and back inside same day. Will only be a few hours so they can get some fresh air and sun. Is rain ok, and how heavy?
Well, you don't want to leave them out in a gale/hurricane.

Short of that, I'd say use your best judgment/common sense—if you're concerned about the weather, bring them in. Peace of Mind.
Also if I did build one, how should it look/be? The only thing I know to do is add lots of plants for shade and protection.
That's pretty much up to you. Since you'll be bringing the whole enclosure in & out each day (vs. just the chams), weight will be a factor, so think.... "Enclosure—
Light"

I would leave out the center piece plants in favor of "bushier" climbers & hangers, and where possible, make use of existing plants/shrubs to help provide privacy & protection (from view).
I also have a lot of outdoor cats that come in my yard (they aren’t mine, I have neighbors with them and they drive me nuts) should I be worried about the cats and my chameleons?
I would. Can you shoot the cats as varmints threatening your chameleon livestock?

IMO, they'll need some sort of cat-proof protection. Half of my brain says, "hang them up high," while the other half screams, "Are you nutz‽ That doesn't stop squirrels from getting to bird feeders!"
If anyone has built outdoor enclosures can you show me your setup? Also I will need a solid divider between the enclosures obviously so they don’t see each other. Will this be affected if it’s windy? Thanks so much.
Definitely.
Quite a few folks here use
butterfly cages—light, airy, inexpensive, and collapsible during the off-season.
https://www.google.com/search?q=but...HacjDYUQ_AUoAnoECAEQBA&biw=1024&bih=625&dpr=1
and the archives...
https://www.chameleonforums.com/search/1635338/?q=butterfly+cage&o=relevance