Right now in Rancho Cucamonga, the air is about 77°F, but the model estimates the asphalt under your dog's paws is closer to 77°F — the surface and air have nearly converged because the pavement is shedding the day's stored heat after dark. That reading puts Rancho Cucamonga in the clear for an ordinary walk. Air temperature alone would have told you none of this — the pavement, not the forecast, is what your dog actually stands on.
Across the 22 hours left today, the pavement in Rancho Cucamonga is projected to top out near 156°F around 2 PM, when the air will be about 105°F — a 51°F gap between the forecast your weather app shows and the surface your dog walks on. Today breaks into 2 separate safe stretches rather than one continuous window, so missing the first does not cost you the day.
In an average August, Rancho Cucamonga sees highs around 94°F and overnight lows near 66°F. At highs like that, sun-baked pavement can easily top 120–130°F by early afternoon, so the walkable hours cluster around dawn and after sunset. As a seasonal rule of thumb, the safest windows are before about 9:00 AM and after about 6:00 PM.
Rancho Cucamonga loses its all-day safe window in 6 months of the year — April through September — and August is one of them. The year peaks in August at an average high of 94°F against 63°F in January, a 32°F swing that decides how much of the day belongs to your dog.
Rancho Cucamonga sits about 4 miles from Ontario, 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. Conditions in Rancho Cucamonga are on the gentler side right now, but keep the same habits: water before and after, grass over asphalt, and a close eye on flat-faced breeds, seniors, and puppies, who overheat and burn sooner than a healthy adult dog.