It’s so hot right now, it’s important to hydrate properly, even if you’re just out walking around.  That means keeping sodium and electrolytes in your body.  In other words, when it is this hot, water alone is not good enough.  I am a big fan of the Nuun tablets.  One tablet works for 20 oz, and they can be broken in half for smaller bottles.  It’s sort of like Gatorade, but without all the sugar.  You get sodium, potassium, and electrolytes.  A biker told me about them — he was standing in the sports drink aisle with me at the grocery store.  That’s right, you can get them at the grocery store!  Be sure and hydrate!