Dog heatstroke risk checker: is it too hot to walk?

I looked for a tested heat threshold for dogs and did not find one. What does exist is three separate things. NOAA's heat index, which was built for people. A temperature-only walking guide from a UK emergency-vet group, Vets Now, which has no humidity in it and is not peer reviewed. And risk-factor studies that tell you which dogs get heatstroke more often, but not at what weather. The cut-offs on this page are my judgement, built from those pieces. Please read them as cautious guidance, not as science.

How the cut-offs move

• Start: a healthy adult dog on a walk in shade. Take care from 24 °C feels-like. Not safe from 28 °C.
• Each of these moves both lines 4 °C lower: one risk factor (two or more move them 8 °C), running or hard play, and direct sun.
• Resting in shade moves both lines 4 °C higher.
• Floor: the lines never drop below 16 °C and 20 °C.

Example: a Pug (one risk factor) on a walk in open sun is two steps stricter, so Take care starts at 16 °C and Not safe at 20 °C feels-like. With the same Pug in the shade, the lines are 20 °C and 24 °C.

The table is made by the same code as the checker above. Every row assumes shade. Direct sun moves each result one step toward Not safe. “Flat-faced” stands for any dog with one risk factor.

Look at the pattern, not one cell. At 24 °C and 90% humidity, a cool Kerala morning, a healthy dog on a walk in shade is rated Take care and a flat-faced dog Not safe. From about 28 °C, a walk is Not safe for every dog in the table.

The formula is NOAA's. In order: compute the simple Steadman formula and average it with the air temperature. If that is below 80 °F, the simple result stands. Otherwise use the Rothfusz regression, then apply NOAA's low-humidity adjustment (below 13% humidity, 80–112 °F) or high-humidity adjustment (above 85% humidity, 80–87 °F) where they apply. NOAA says it can give meaningless results outside the range of its chart, about 80–110 °F and 40–100% humidity. In that case this checker still shows a number, tells you it is outside the chart, and never lets the feels-like drop below the air temperature.

I compared the code with all 135 numbered cells of NOAA's heat index chart. 133 are within NOAA's stated ±1.3 °F, and 125 match after rounding. The other two (80 °F at 95% and 100% humidity) come out 1.8 and 2.3 °F higher, because NOAA's written method adds the high-humidity adjustment and the printed chart does not. I kept the adjustment, because it errs towards caution for a dog.

One more limit. The 1990 NWS note describing the equation says it models a 5 ft 7 in, 147 lb person walking outdoors at 3.1 mph in long trousers and a short-sleeved shirt. A dog is a different animal in every way that matters here: coat, no sweat, panting, body temperature, airway. That is why this is a stand-in, not a measurement.

Dogs cool mainly by panting. They can only sweat through the bottoms of their feet (Texas A&M College of Veterinary Medicine), so they rely on evaporation from the airways. Panting is an important part of how a dog gets rid of heat (Hall 2020, Animals).

Humid air already holds a lot of water, so less evaporates. A Texas A&M emergency and critical care specialist says that once humidity reaches about 85%, evaporative cooling is almost totally inhibited. Hot and highly humid conditions are a recognised risk factor for heatstroke in dogs (Bruchim 2017), and Cornell says dogs are most at risk when they exercise in hot and humid weather.

Kerala has both. Onmanorama, reporting on India Meteorological Department and Kerala State Disaster Management Authority warnings in April 2026, said the state's high humidity amplifies the felt temperature, making it significantly higher than the recorded temperature.

What the UK studies can and cannot tell you

Most of the published numbers come from UK dogs. They tell you who is at higher risk. They do not tell you what is safe in Kerala, where ordinary weather is much hotter and more humid than in those studies. I found no published study of heat illness in Indian dogs, so I did not invent breed multipliers for them.

Do dogs get used to the heat?

Heat acclimatisation affects the risk (Hall 2020, Animals), and lack of acclimation lowers survival in dogs with heatstroke (Bruchim 2017). A dog that has lived in Kerala all its life copes differently from a dog that has just arrived. But I found no study giving a safe walking temperature for acclimatised dogs, so the checker does not relax the bands for it.

Stop, get your dog into shade, and read the first-aid guide if you see any of these. The three groups follow the VetCompass clinical grading tool (Hall 2021). The colour of this checker does not matter once your dog has any sign.

• Early signs: panting heavily or struggling to breathe, tiredness, stiffness. Panting that carries on after you stop and rest in shade is a warning sign (Hall 2020).
• Serious signs: vomiting or diarrhoea, drooling or foaming, collapse that comes and goes, a single fit. PDSA also lists bright red gums or very pale gums as a moderate sign.
• Also listed by the RSPCA: noisy breathing, red gums and tongue, muscle spasms, confusion.
• Life-threatening signs: wobbling or staggering, more than one fit, deep drowsiness or no response, bloody vomit or diarrhoea, bleeding.

In the UK data, about 2% of dogs graded mild died, about 5% of moderate and about 57% of severe, counting euthanasia (Hall 2021). Those are population figures, not a prediction for your dog.

Press the back of your hand on the ground for seven seconds. The Royal Kennel Club says if it is too painful for your hand, it is too hot for your dog's paws. Dogs Trust gives the same test as five seconds. I use the longer, more cautious one.

This is a common rule of thumb for paw burns. I found no study that tests it in dogs. It says nothing about the air or the humidity, so a dog can still overheat on ground that passes the test. The Royal Kennel Club says pavements are usually much warmer than the air on sunny days. If paws look red, swollen or blistered, or your dog limps or whimpers, get off the surface and call your vet.

• Dogs Trust says early morning or later in the evening. The Royal Kennel Club says early morning or evening, and avoid the midday sun. Both are UK advice. In Kerala I would take that to mean around sunrise or earlier, and after the sun is down. That is my judgement.
• I do not have a published set of hours for Kerala. As my own rule, treat roughly 10 am to 4 pm as the time not to walk. That is judgement.
• Check the numbers at the time you go, not the forecast for the day.
• Keep walks short on warm, humid mornings. Do nose games and training indoors with a fan or AC.
• Carry water and offer small amounts often.
• Choose grass or earth over tar when you can, and do the hand test on any hard ground that has been in the sun.

In a test over 16 sunny days, the inside of a dark car rose by about 40 °F on average in an hour, and reached 117 °F even on the coolest day (72 °F outside). Most of the rise happened in the first 30 minutes, and leaving the windows open a little did not slow it (McLaren 2005, a study of enclosed vehicles). The Royal Kennel Club says never leave your dog in a car, even with the windows down, and Dogs Trust says a dog can die in a hot car in minutes.

In UK dogs, vehicle confinement raised the odds of severe illness about threefold compared with exertion (Hall 2022), and dogs confined in buildings had about six times the odds of dying (Hall 2020, Animals). A shut room, a closed van and a parked autorickshaw are the same danger.

• It cannot examine your dog. It is general education, not veterinary advice.
• It does not know the wind, the heat from tarmac, your dog's coat colour, fitness, or how well it is used to heat.
• A weather app gives a figure for the city, often from one station. In a small study in Alabama, 8% of the hours measured at dogs' collars fell in the NWS Danger or Extreme Danger categories, while nearby weather stations never did (Moon 2021). Your street can be hotter than the app says.
• Fit, working dogs can handle more than the checker allows: in one study, young working dogs exercised at 28.9 °C and 47% humidity reached an average core temperature of 40.1 °C and none needed medical treatment, though one reached 42.4 °C (Robbins 2017). Pet dogs are not those dogs, and the checker is cautious on purpose.
• Safe is not a promise. If your dog shows any warning sign, ignore the colour and act.