We know it sounds weird, but if it's hot out, you should grab a hot drink!
Research shows that a hot beverage will actually help you cool down in the long run, if you're not already hot and sweaty.
"When we take in a hot drink, it appears that the thermosensors located in the stomach become overactive, and send strong signals to our hypothalamus that we are hot. In turn, the hypothalamus reacts by initiating an over-compensatory sweating response. So, when this sweat evaporates from our skin, the heat energy we lose due to evaporation exceeds the heat energy gained by drinking the hot drink. In other words, it is because our body overacted to the hot drink that we end up cooler in the end." -Yahoo! Health