What is "too hot" for a walk?

Dogs need to go on walks, right? I hear that from pretty much every dog trainer I interact with. Everyone agrees: dogs need to walk. They need it for exercise, socialization, and training purposes.

So up until this ungodly summer, I was walking Star regularly. And it was going pretty well. Star walks great on a leash, and I've found her to be very reliable in worst-case scenarios (off-leash dogs charging us) as long as I keep my cool, say "leave it," and keep walking.

But now it's in the 100s every day. We have no sidewalks; you either walk on the asphalt or the grass. At these temperatures, asphalt is not an option for dog paws, and the grass isn't really grass, it's sticker burrs, fire ant mounds, broken glass, and automobile fluids.

I've been walking with Star at 10 PM for the last few nights, when the temperature drops into the 90s... but the asphalt still feels hot beneath my feet, and it's so dark that I can't see the broken glass, ant mounds, and all the rest. It's also too dark to see loose dogs and suspicious people; thank goodness the dog we ran into last night was a bit lost and frightened, but not really aggressive (Star and I helped it find its home after I made sure it was friendly). And because we're not walking on a sidewalk, it's not much distance between us and passing cars.

Walking in the morning might be a better option, because it's only in the 80s and the pavement is cooler. But I'm not a morning person...

And then there's Star. She's got no stamina at all. She's good on a walk for about five minutes, then she's just HOT. I swear she acts just like a two-year-old child, dragging her feet and mentally willing me to pick her up and carry her.

My final option is to build an enormous mirror and reflect all the heat back toward the sun, a la Futurama.