His SS looks incredible. Keep in mind that there is a 20% meter variance between readings on the same meter so 94 and 102 are pretty much the same number.
Having said that, insulin is a hormone and not a medication and many things can change it including, yes, barometric pressure. We don’t always know why the BG changes from (although I’d say his changes are tiny compared to most). BGs can change a bit as cats age and maybe get a bit of arthritis or have some other minor medical issue. But it can be really subtle stuff like, the change in seasons. My Gracie always had better BGs in the spring and summer and horrible ones in the fall.
As long as he’s feeling good, I wouldn’t worry. When I flip back through his SSs from different years, honestly, I don’t see much difference. You are doing a great job with him ind ether mining when he needs more insulin so just keep doing what you are doing and don’t stress if he needs a bit more from time to time.