Drinking hot tea when it's so hot outside seems like the complete opposite of what you should do, but it's not such a crazy idea.
This story by Joe Palca of NPR's Morning Edition explains why drinking hot tea on a hot day can help cool you down:
For my next installment, Morning Edition Executive Producer Madhulika Sikka asked me to explain why drinking hot tea cools you off on a hot day.
"Trust me," she said. "I'm Indian, I'm British. A billion Indians can't be wrong. They drink hot tea in hot weather." [...]
There are all sorts of receptors in all sorts of nerves, but the nerves in the tongue have a lot of one particular receptor that responds to heat. It's called the TRPV1 receptor, if anyone wants to know.
So when you eat or drink something hot, these receptors get that heat signal, and that tells the nerve to let the brain know what's going on.
When the brain gets the message "It's hot in here," it turns on the mechanism we have to cool ourselves off: sweating.