Always important to stay hydrated but in the super dry southwest it is easy to get yourself in trouble before you realize it. You work in that heat without even busting a sweat and if you don't make yourself drink a lot of water, by the time it hits you you could already be in real trouble.
When I worked in Iraq, they were serious about the hydration thing. Anyplace on the bases that had indoor plumbing would have a color chart posted of the wall above the urinals. The clearer your piss the better.
They have a similar chart posted in the men’s bathroom at the Walmart DC in Wintersville,Ohio
In the upper Midwest you have a combination of high heat and humidity. I’m currently in Tomah,Wisconsin and the last week there was at least 5 straight days of temperatures in the low to high 90s. Last night we had severe thunderstorms roll through the area to cool things down but today it shot back up into the mid 90s again. Been swilling fluids ever since.