but of course if the weather is hot then it is advised to drink cold water.
It's actually marginally better to drink warm water on a hot day, rather than cold water. Apparently, your body works harder to adjust the cold temperature of the water to your body and cool you down faster. The warmer temperature also encourages sweating (seems counter-intuitive) however is a natural response that can cool you down as long as you're letting the sweat evaporate into the air rather than getting it trapped into thick layers of clothing.
I'm not sure there is sufficient evidence that makes this certain, but at least that's what I've read.