The heat causes some to break under the pressure of it all. So we've been through how to talk to her, and how to not act like a complete fool. You like her, and want to be with her. Now the time has come to finally ask her the big questiong!
Asking her out.
So, it's time for you to just do it. Only don't die under the pressure. The heat causes everyone to choke, and the nerves get out of control. Just take a deep breath, say I can do this and just walk over to her. The heat is nothing compared to how happy you'll be. Just think about what you are doing, and how you'll be ecstatic when she says yes.
Not if, but when.