How your dog's heat and cold risk works
Why the ground and your dog are two different questions, how the heat risk and the winter cold bands are worked out, and where the numbers come from.
From version 1.1, Pavement Paws shows two things. The Today card is about the paws: how hot the ground gets. The heat risk card is about the whole dog: how hard the weather is on its body, wherever you walk. They can disagree, and that is correct. A large dog with a thick coat can overheat on cool grass.
What it measures
Dogs cool themselves almost only by panting. Four things decide how well that works: the air temperature, the humidity (sticky air makes panting cool less), the wind, and the sun on the coat. Pavement Paws combines all four into one number, the WBGT (wet-bulb globe temperature). It is the heat-stress measure used in sport and by armies, and the one a large UK study of dogs with heatstroke used.
The app estimates it from your local forecast, hour by hour. Part of it is how much the humidity holds back cooling; part of it is how hot a black ball gets standing in the sun, which is much how a dark coat heats up. Without the sun that part drops away, which is how the card can tell you what shade buys you today.
The levels
| WBGT in the sun | Level | What to do |
|---|---|---|
| below 18 °C | Fine | Normal walks. On long, hard play, watch for heavy panting. |
| 18 to 22 °C | Take it easy | Walks are fine; keep play gentle and bring water. |
| 22 to 26 °C | High | Short, slow walks in the shade. No fetch or running. |
| 26 °C and up | Danger | Only quick toilet breaks in those hours. Walk before or after them. |
Why the warnings come sooner for some dogs
Each of these moves every level 2 °C earlier:
- a flat face (pug, bulldog, French bulldog, boxer and the like),
- a puppy or a senior dog,
- extra weight,
- a large dog,
- a thick coat.
The first three come from the research below. Large dogs and thick coats are our own judgement: heavier dogs get worse heatstroke in the UK data, and thick-coated breeds such as the Chow Chow and the Golden Retriever are among the most affected, but no study gives a number for them. Set these under Settings › Your dogs.
Where the numbers come from
No study gives a WBGT limit for pet dogs directly, so the levels sit between what the research shows:
- Royal Veterinary College, VetCompass (a 2022 study): 856 UK dogs treated for heatstroke. On those days the highest WBGT was usually 15 to 19 °C, measured in the shade, which is about 18 to 22 °C in the sun. Most cases with a known cause followed exercise, 71 %. Old and flat-faced dogs died more often.
- Military working dogs (reviewed in the same paper): three quarters of heatstroke cases above a WBGT of 26.7 °C. These are fit dogs used to heat, so pet dogs struggle sooner.
- Dogs on walks in the sun (a 2026 study): five short-haired dogs walked 135 times in Brazil. When a black globe in the sun passed 35 °C, their coat warmed by 20 °C and they panted up to about 300 times a minute. The reason the app counts the sun on the coat.
- Israel (a 2006 study): 46 of 54 dogs with severe heatstroke were exposed to a heat index of 24 °C or more.
We checked the levels on every day of 2025 in central Belgium: an ordinary dog would have had 11 Danger days (the heatwaves) and 37 High days, with the first “Take it easy” in early April.
In winter: the cold bands
On cold days each dog gets a band for the day instead: Fine, Coat on, Short walks or Quick breaks only, with the best time to go.
What it measures
The starting point is how cold the weather is for a person outdoors, measured with the UTCI (Universal Thermal Climate Index). It is the international standard behind Europe’s Copernicus heat and cold stress maps, and like the WBGT it combines air temperature, humidity, wind and sun. It weighs wind heavily, so a day with an icy wind shows up as the cold day it is: on 9 January 2026 in Brussels the air was +4 °C, but a 10 m/s wind made it “strong cold stress”. The sun counts too, which is why a frosty morning can turn into a fine afternoon.
The app works the UTCI out from your forecast hour by hour, with the official formula (Bröde and others, 2012).
The levels
A typical dog (medium or large, adult, a normal coat) copes with the cold about as well as we do:
| UTCI cold stress for a person | Typical dog |
|---|---|
| none or slight (above 0 °C) | Fine |
| moderate (0 to -13 °C) | Fine |
| strong (-13 to -27 °C) | Coat on |
| very strong (-27 to -40 °C) | Short walks |
| extreme (below -40 °C) | Quick breaks only |
A small dog, a puppy or a senior dog each moves one step sooner, so a small senior dog needs a coat in slight cold stress and short walks in moderate. A thick coat moves a dog one step later.
Where this comes from, and how sure it is
The human side is a standard. The dog side is our judgement, and it is weaker than the heat side, because the research is thinner:
- There is no study of pet dogs harmed by cold like the VetCompass heatstroke study, and Purdue University’s Center for Animal Welfare Science notes there is no scientific data on safe temperatures by breed, age or coat.
- What the research does agree on is the direction: small, light dogs lose heat fastest (a 2025 study of dogs across seasons), puppies and old dogs cope worst, and a thick coat protects. Those are the steps the app uses.
- The US military’s guideline for working dogs in the cold (2026) links hypothermia to long exposure and frostbite to freezing air, worse when wet or windy. It sets no limits for walks.
Icy ground and paws
When the ground freezes, the app also says when it is icy. The pads of a dog’s feet stay warm on cold ground thanks to a heat exchanger in their blood vessels (Ninomiya and others, 2011), so the cold itself is rarely the problem for paws. Grit and road salt are: they sting and dry the pads. After snow on frozen ground the app says so; wipe the paws after the walk.
What it is not
It is an estimate from a forecast, not a measurement of your dog, and not a diagnosis. Heatstroke can happen on mild days during hard play, and fitness, age and health matter more than any table. Stop when your dog pants hard, slows down or seeks shade, and call a vet if it staggers, vomits or seems confused. In the cold, bring your dog in if it shivers hard, lifts its paws or slows down, and keep it dry: wet fur loses heat much faster.
The globe estimate will be checked against a real black globe during the spring calibration, together with the pavement model.