There is also a gov. Guide for what is too hot by age. I wouldn't take my baby out in the carrier at 90 degrees, your body heat will mAke the baby hotter as well. Can you go for a walk around the mall?
I'm here in Houston also. We try to go early in the morning or late in the evening. I haven't used my carrier yet but usually use the car seat and jogging stroller. I'm worried that he may get too hot in the carrier he's already a sweaty kid.
I've done it in a woven wrap and kinderpack in similar weather, but I keep to the shade and keep a close eye on how warm she feels. I also have some of the frog togg chilly pad things to help if I'm concerned about overheating, and I make sure I'm somewhere I can get into the air conditioning quick.
I live in Houston too but we try to go in the morning (Ha.. I'm catching up on sleep now), or an hour before sunset. We use the stroller/car seat combo, and will use the ergo carrier more when it cools down.
Re: 90 Degrees too hot?