It's more than hot (this coming from a Texan), and it's VERY VERY crowded - peak time to visit, lots of people.
Since we have other options, we won't visit that time again - I couldn't handle the constant heat and lines. But lots of people go each year at that time, and have a great time regardless. Just be prepared with water bottles, take lots of breaks, take advantage of EMH and fast passes, don't rush, and enjoy the AC when you can =)