That’s a tough one—honestly, I’ve seen caulk turn into a sticky mess if it’s too hot out. Most of those adhesives are rated for certain temp ranges, but when it’s blazing, they just don’t cure right. I get wanting to get it done, but sometimes waiting for a cooler stretch saves you from redoing the whole thing later. Been there myself and learned the hard way... patience pays off with this stuff.
I hear you about the caulk getting weird in the heat, but I’ve actually had decent luck swapping out two windows in late July a couple years back. It was one of those situations where waiting just wasn’t an option—AC was leaking out like crazy and the old frames were basically falling apart. I did end up using a different type of sealant meant for higher temps, and I kept all my supplies in the basement until the last minute. Worked early in the morning before things got too brutal outside.
Not saying it’s ideal, but sometimes you just have to weigh the risk of a less-than-perfect cure against living with drafty, busted windows for another month. I was extra careful about smoothing the bead and checked it a few times as it set. Maybe I got lucky, but two years later, no issues yet. Guess it depends on how desperate the situation is and if you’re willing to baby it a bit during the curing process.