Well everything is hot right now anyway. Especially our local waters. Here's some tips to keeping cool, hydrated and saving fish from dying as you release them.
Bring water, gatorade, powerade, vitamin water, orange juice, apple juice, tea, lifewater...ok you get the drift, I hope. Lots of fluids if you are floating or wading. Just because you are wading knee deep in water does not mean you are hydrating. You actually have to ingest a liquid to keep hydrating and hydration keeps you cool. Drinking from rivers, especially when it is this warm is not recommended as bacterial and parasitic counts go up, such as Giradia aka Beaver Fever. And no, as much as I wish it were true, beer, alcohol, and soda do not hydrate you, they actually dehydrate you, so think about that before you fill the cooler full of Rainier.
Along the same lines, when it is this hot outside, skin protection is key to keeping the ability to stand upright. Heat stroke, sunburn, and heat exhaustion can happen quite quickly, especially in high heat/high humidity days. So sunscreen is a good idea, but cover yourself with a long sleeved shirt, wide brimmed hat and yes, even polarized sunglasses, will prevent such things from happening. Sunscreen can only do so much and in the long run a long sleeved shirt will actually keep you cooler and save on days of pain, trust me.
Lastly, check water temperatures to the places you are going. If you care about fish like we do, anything with a water temp above 65 degrees it's probably a good idea to leave the water dwellers alone. Higher water temps equate to lower dissolved oxygen content in the water and puts extra stress on them. Simply put, a fight on the end of a fly-rod could just plain kill them.
Best bet this week. The salt water if you want to fish. The rivers are for rubber hatches and staying cool, among other things. Have a blissfully hot week.