This isn't normal heat for May in the Northeast... Although it could be the new normal.
It looks like next week is going to be more like springtime.
But if you're not used to heat like this, there are a few very helpful tips. First, hydrate all the time, like all the time. All day before you run and all day after you run. Next, soak your shirt in water and wring it out afterwards. The evaporation helps loads. And for post run, cold showers, or at least cool showers. You'll feel great afterwards.
Electrolytes electrolytes electrolytes!!
You'll adapt. Eventually...