i wear abayah, and in hot weather i wear thin one, with few chiffon clothes underneath. they do not have to be heavy weight. in fact i find it cooler when the sun is not on my skin and wearing loose clothes as the air circulates inside my abaya, and catches every little breeze.
if you dont believe me try it, wear an abaya, and khimaar with vest top underneath for a few hours and see how it feels.
in hot weather we are all hot, not just those who cover.
my dd is 4 and doesnt wear abayah or hijab.
my other dd3 loves hats and headscarfs, the same way kids like to wear there mums shoes, they like to copy their headscarfs, so many kids want to wear it.
long sleeves and legs in hot weather prevents sun burn.
it is not required before puberty to wear it, but instead of suddenly sayin now you have pubic hair etc wear a scarf, some people like to take a more gradual approach, and get their kids used to it.
personally i would want my kids to come to their own decision and wear it when they feel they want to, and understand the reasoning behind it, theres no point in forcing someone to wear it, as so many have said they just take it off round the corner.
did the other kids not look hot in the hot weather?
in primary schools kids are under no obligation to wear the uniform. my dd has been wearing a pink cardigan as she lost her blue one, no one cares.
in secondary school we werent allowed to wear trousers so muslims wore longer length skirts.
we werent even allowed to wear hair bands that werent the school colours so wearing non school coloured scarves was unthinkable.