Of course it gets hot - everyone gets hot in 30 degrees but from my pre-hijab days there isn't a great differance. I guess it depends on how adept you are at dressing for the heat. I find that a loose skirt in a pale colour and a loose top in a light fabric is not really hotter than shorts and a t-shirt. I imagine that for those who choose to wear heavy dark clothes it's a lot hotter.
I read somewhere that in some ways the style of the traditional Islamic dress for both men and women evolved out of a practical requirement to keep cool and reduce sun exposure in hot climates as well as being an expression of modesty. I'm not sure if that is true or not...?