What are the best carriers to use in super, SUPER hot weather. DS and I are both hot natured and we are both drenched in sweat at the point of contact within a few minutes of babywearing. I'm afraid he gets overheated and that's why he sometimes acts like he doesn't like being worn.
Due to severe back pain, I use my mai tai for things like grocery trips and I have a thin, cotton, ring sling that I use for very short durations sometimes, but even in that we get all sweaty.
Honestly, I wore my ring sling with nothing but a bra unless we were out of the house, and then I just lived in nursing tanks. I think when the weather is hot there's really only so much you can do. I actually wonder if thicker fabric between you would help...it might help with the body heat part of the problem, anyway? Sigh, good luck. Too bad we're heading INTO summer. By the time I really started wearing, it was around the end of August, so there was a glimmer at the end of the sweaty tunnel.
Kole being against you is going to be warm. Not much you can do about that. However, he WILL let you know when he's too hot being worn. Dress yourself in cotton fabrics and keep him in just a onesie at most. I did find myself in TX using the stroller for outdoor events like hanging in the park, going for walks, and going to a festival when the temps were in the upper 90s plus (which it was 100 plus most of last summer *sigh*). I used carriers when shopping, on random "cool" days outside, and around the house. I found myself wearing more outside when we were out of town because 90* and a breeze seemed soooo cool compared to 100+!
As far as carriers go, there are more lightweight carriers that will keep the baby cooler. If you're willing to try wrapping, you can find cotton gauze for pretty cheap at times. You can hem it yourself. Just a word of the wise, keep it wider (fold it length wise if you need to at first) because it will be supportive for longer. I made the mistake of cutting mine in half to make two wraps and it wasn't wide enough by 5 months and weighted on me heavier than Mara's DIY gauze did on her. It is VERY COOL and wrapping can be very supportive on your back as long as you keep the back passes spread nice and wide. Front cross carry is a poppable carry (so works like the Moby). Front wrap cross carry is very supportive, though it adds layers (which is why it's so supportive). Kangaroo carry is very cool on baby, though I don't have that up on here yet cause I haven't done that since Aiden was a baby.
And if you really need to wear him outside, like chasing Lyla around the yard, I've read that some people have had success with a small ice pack wrapped up in a towel or similar and placing it between them and the child.
I've been thinking about your back issues and I realized that back carries have always been better on my back than front carries. I also feel cooler with a back carry. So definitely work on those once he has good head control and you feel brave!
Switching to back carries is going to revolutionize your BWing. I guarantee it.
Maybe I'm just a wimp but I don't tend to hang out outside much when it gets over ~95. I'll consider it if there's significant shade, a breeze, and perhaps access to a mister (I made DH install one on the back porch when I was PG). But no really, I'm a wimp. Summers here are our "winter" months when everyone hides inside or in a pool. Winters are for getting outside and enjoying the weather! The only carrier I was ever uncomfortable in and that I felt was too warm for DD was the Moby and even then it was probably more uncomfortable for me than for her. She may have been born in the end of Sept but we had a good month and a half of 90+ temps while she was still a NB. My ring sling is just some cotton weave and its black and I was never so warm that it was too warm. I hadn't gotten my mai tai until Dec and by the time it warmed up again the next year I couldn't use the ring sling anymore because T was just too heavy. If you feel its too warm to be wearing him in a ringsling its probably too warm for him to be outside, period.