Right now in Lowell, the air is about 63°F, but the model estimates the asphalt under your dog's paws is closer to 63°F — the surface and air have nearly converged because the pavement is shedding the day's stored heat after dark. That reading puts Lowell 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 18 hours left today, the pavement in Lowell is projected to top out near 85°F around 5 PM, when the air will be about 72°F — a 12°F gap between the forecast your weather app shows and the surface your dog walks on. The surface is still gaining — up about 6°F over the next three hours — so a walk taken now is cooler than the same walk later this afternoon.
In an average August, Lowell sees highs around 82°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 12:00 PM and after about 4:00 PM.
Lowell loses its all-day safe window in 3 months of the year — June through August — and August is one of them. The year peaks in July at an average high of 84°F against 37°F in January, a 47°F swing that decides how much of the day belongs to your dog.
The nearest place we track is Cambridge, about 21 miles away. That is close enough to move together in a heat wave but far enough that a passing cloud bank or a coastal breeze can put real distance between the two readings, so check Lowell's own page rather than assuming.
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 Lowell 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.