Right now in Thornton, the air is about 82°F, but the model estimates the asphalt under your dog's paws is closer to 120°F — a gap of roughly 38°F, because clear skies are pouring full sun onto every dark surface. That reading puts Thornton in the caution range, where short, shade-hugging walks are the most a paw should take. Air temperature alone would have told you none of this — the pavement, not the forecast, is what your dog actually stands on.
Across the 10 hours left today, the pavement in Thornton is projected to top out near 120°F around 2 PM, when the air will be about 82°F — a 38°F gap between the forecast your weather app shows and the surface your dog walks on. The surface is already coming down, about 23°F over the next three hours, so waiting a little works in your favour here.
In an average October, Thornton sees highs around 66°F and overnight lows near 38°F. That keeps most of the day walkable, though a rare clear, calm afternoon can still warm exposed pavement more than the mild air suggests. For this month the normals suggest pavement rarely reaches unsafe temperatures here, but the seven-second hand test is still the final word on any given day.
Thornton loses its all-day safe window in 4 months of the year — June through September — and October is not one of them. The year peaks in July at an average high of 89°F against 39°F in January, a 50°F swing that decides how much of the day belongs to your dog.
Thornton sits about 4 miles from Westminster, close enough that the two usually run within a degree or two of each other — if your walk crosses between them, either page answers the question. Street-level conditions still differ more than city-level ones do: a shaded side street and an open parking lot half a block apart can be twenty degrees apart underfoot.
Whatever the number says, confirm it with your hand: press the back of it flat on the pavement for seven seconds. If you can't hold it there, neither can your dog. On a day reading this warm in Thornton, flat-faced breeds like pugs and bulldogs, plus seniors and young puppies with thinner pads, should sit out the heat entirely — subtract about 10°F from any safe threshold for them. If you must cross hot ground, protective booties or a quick coat of paw wax are the only real barrier between paw pads and the asphalt.