Seasonal clothing for Fall Mexico City Wedding

[apolloali]

Folks, I've just overhauled my suiting wardrobe. I usually just wear standard four season weight woolen suits and cotton shirts, which require little thought. But for the first time I've got two seasonal pickups and I need tips.

The first is a heavier flannel-ish vintage Golden Fleece Brooks Brothers checked brown suit. It looks great. But also, trying it on inside, it's so warm! Makes me sweat. The wedding is outside — could I wear it in 55-75 degree weather? It looks like it'll be 65 mostly outside. Chilly is what I've heard from people there now.

And then after that, on the other side, I bought a 50/50ish cotton/linen blend white dress shirt from Spier and Mackay. It's surprisingly soft, not wrinkly, and honestly I wouldn't notice that it's linen. Because it's new and seems comfortable, I'm inclined to wear it because it's new, but my mind thinks that you'd never wear linen with Fall/Winter suits. But I never considered whether a blend could be worn.

TLDR:
Two qs:
Flannel suit, too warm for October in Mexico City wedding?
Can a 50/50 cotton/linen blend shirt go with a Fall/Winter suit? Link to that here: https://www.spierandmackay.com/product/white-twill-linen-cotton-dress-shirt-ry-3452-2c2f5k

Sorry if silly questions! I've just surprisingly never had seasonal clothing items of these two styles.

 

[comrade]

Have you considered something like this:

 

[KlarkKent]

To me it sounds like the suit will be too warm. You'll be around people, moving, hopefully dancing. I think it might need to wait until late fall/winter.