Firstly, cotton cotton cotton if you don't already dress your child exclusively in cotton. Natural fibers are a must-esp in summer. I would use a cotton receiving blanket between baby and seat not just to soak up sweat, but to prevent it. Those covers are polyester and that causes sweating in summer. Also, in addition to a clip on fan, you could simply use the sun shade that comes on the carrier, open it all the way and then tilt it forward so that the sun isn't on baby. I do that. I use no socks or shoes in summer (she's not walking yet, tho) and another great idea would be to carry a little spritz bottle of water w/ a drop or two of peppermint essential oil and occasionally spritz baby to cool down. Be careful for eyes, of couse! HTH