You are not the only one suffering from Portland heat this week: Your Mac is too, along with your DSL/cable modem.
Many people have their Macs set up in a 2nd floor room or converted attic and believe me, it gets HOT up there. If it's too hot for you, it is too hot for your electronics.
As a temporary fix, you can aim a fan at your DSL modem to help it cool off. It does not have its own fan and relies on convection. If you have it covered up or tucked away, you can expect poor Internet performance and outright shutdowns. You can bring it back up by powering it off and then on again, but if it is hot to the touch, take steps.
I moved mine out of its niche onto a tabletop where I could aim an 8" clip-on fan at it and have had no trouble since.
I have installed on (I hope) all of my clients' MacBooks and Pros a copy of the SMC Fan Controller program that alerts you to your processor temperature (in the menubar) along with your current fan speed. If you drop that menu down you will be able to select higher speed. Do that if the temperature ever goes above 130. You will hear the fan, but it won't run down your battery more than a few percent faster and you will really need the cooling.
If you don't have it installed, go to the publisher's site and download it. Launch it, drop the menu down and set the Preferences to °F instead of C, the Default speed to 3000 or so and Higher to the maximum. Also check Load At Startup. Then click Save.
It should always load at restart.
PS: Please call me for an appointment if I have not seen you this year. Your Mac may be accumulating minor errors and other issues that could cause you grief in the future. Better now than some morning when it crashes and won't start up.