Right now in El Cajon, the air is about 79°F, but the model estimates the asphalt under your dog's paws is closer to 87°F — a gap of roughly 8°F, because clear skies are pouring full sun onto every dark surface. That reading puts El Cajon 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 5 hours left today, the pavement in El Cajon is projected to top out near 87°F around 7 PM, when the air will be about 79°F — a 7°F gap between the forecast your weather app shows and the surface your dog walks on. The surface is already coming down, about 13°F over the next three hours, so waiting a little works in your favour here.
In an average August, El Cajon sees highs around 87°F and overnight lows near 64°F. Even at those moderate highs, a dark surface in direct sun can run 40–60°F hotter than the air, which is enough to tip midday walks into the caution range. As a seasonal rule of thumb, the safest windows are before about 10:00 AM and after about 5:00 PM.
El Cajon loses its all-day safe window in 5 months of the year — May through September — and August is one of them. The year peaks in August at an average high of 87°F against 64°F in February, a 23°F swing that decides how much of the day belongs to your dog.
El Cajon sits about 13 miles from Chula Vista, 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 El Cajon 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.