Frequently Asked Questions
How StableWeather calculates horse-specific weather safety thresholds, and where the science comes from.
How does StableWeather calculate the equine heat index?
The equine heat index is calculated by adding the air temperature (°F) and the relative humidity (%) together. This simple formula is widely used by equine veterinarians and organizations like the American Association of Equine Practitioners (AAEP) to assess heat stress risk in horses.
Horses cool themselves primarily through sweating and evaporation. When humidity is high, sweat doesn't evaporate efficiently, which means the horse can't regulate its body temperature — even if the air temperature doesn't feel extreme to a human.
Horses can thermoregulate effectively. Normal training and turnout schedules are fine.
Cooling becomes less efficient. Reduce workout intensity, provide shade and water, and watch for signs of heat stress: excessive sweating, rapid breathing, or lethargy. Horses with anhidrosis (non-sweaters) are at elevated risk.
The horse's cooling mechanisms are severely compromised. No strenuous work. Ensure constant access to fresh water and shade. Consider hosing down horses. Risk of heat stroke, colic, and organ damage is real at these levels.
What wind speeds are dangerous for riding?
Wind thresholds for riding are based on practical safety considerations — both for the horse's behavior (spooking, refusal) and for physical hazards like airborne debris, falling branches, and compromised visibility in dusty arenas.
Normal riding conditions. Some horses may be more alert than usual in gusty conditions even below this threshold.
Many horses become reactive in sustained winds above 20 mph. Loose objects can blow into arenas. Trail riding is inadvisable due to falling branch risk. Inexperienced riders should avoid riding in these conditions.
Do not ride. Structural damage to barns, fencing, and arenas is possible. Horses should be in secure shelter. Flying debris is a serious injury risk for horses and humans alike.
How are footing conditions determined?
Footing assessments are derived from weather conditions — temperature and precipitation — since we can't measure your actual arena surface remotely. These are indicators to help you plan, not a replacement for walking your footing before you ride.
Ground is likely frozen hard. Riding on frozen footing increases concussion injury risk to joints and hooves. Even well-maintained arenas become dangerously firm. Turnout on frozen pasture can cause bruised soles.
Saturated footing is slippery and can cause soft tissue injuries from loss of traction. Deep mud increases tendon strain. Sand arenas may become too deep; grass surfaces become slick.
Conditions are favorable for safe footing. Always verify by walking your arena — weather conditions are an indicator, not a guarantee.
Prolonged heat without rain can harden natural surfaces and cause excessive dust in sand arenas. Dust is a respiratory hazard for horses. Consider watering your arena before use.
What freeze thresholds does StableWeather use?
Freeze warnings are important for barn management — frozen water troughs, ice on walkways, and blanket decisions all depend on knowing when temperatures will drop below freezing.
Uninsulated water lines and troughs will freeze. Stock tank heaters should be active. Check automatic waterers. Blanketing is recommended for clipped horses, seniors, and horses without adequate shelter.
Standing water will freeze. Check troughs, especially in exposed areas. Mud and wet ground may freeze into dangerous uneven footing. Hose bibs should be drained.
Not yet freezing, but overnight temperatures may dip below 32°F — especially in low-lying areas and near water. A heads-up to prepare.
Where do the lightning and severe weather alerts come from?
Severe weather alerts on StableWeather come directly from the National Weather Service (NWS) via their public API. These are the same official alerts issued by your local NWS forecast office — the same ones that trigger Emergency Alert System (EAS) broadcasts and Wireless Emergency Alerts (WEA) on your phone.
We display alerts specific to the exact coordinates of your searched or saved location. Alert types include:
Seek shelter immediately. Horses should already be in a sturdy structure if possible — though in practice, the safest option for horses in a tornado is often an open field rather than a barn that could collapse. This is a judgment call that depends on your specific structures.
Lightning, high winds, and hail are imminent or occurring. Bring horses in from pasture. Do not ride. Lightning is the number one weather-related killer of horses — they are tall, often in open fields, and frequently near metal fencing and water.
Conditions are favorable for severe storms. Plan to bring horses in if storms develop. Have a plan for where horses will go — not all barns are safe shelter in severe wind.
Where does StableWeather get its weather data?
StableWeather uses publicly available, government-operated weather data sources:
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NWS
National Weather Service API
All location forecasts, current conditions, and severe weather alerts come from the NWS. This is the same data that powers weather.gov and that your local TV meteorologist uses. Forecasts update approximately every hour.
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GEFS
Global Ensemble Forecast System
Our spaghetti plots are generated from the GEFS — a 31-member ensemble model run by NOAA/NCEP. Data is downloaded every 6 hours from the NOMADS server and processed on our own hardware using MetPy and Matplotlib.
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ASOS
Automated Surface Observing System
Current conditions (temperature, humidity, wind) come from the nearest ASOS/AWOS weather station, accessed through the NWS observations API. These are real-time instrument readings, not model estimates.
Is StableWeather a substitute for veterinary advice?
No. StableWeather provides weather-based safety guidance for general planning purposes. It is not veterinary advice, and it does not replace the judgment of an equine veterinarian, your trainer, or your own knowledge of your horses.
Every horse is different. Age, breed, fitness level, acclimation, coat condition, and medical history all affect how a horse responds to weather. A clipped, stalled Thoroughbred and an unclipped, pastured Icelandic have very different cold tolerances. A horse with anhidrosis (inability to sweat) is at extreme heat risk even when our heat index shows "safe."
Use StableWeather as one input in your decision-making — not the only one. When in doubt, consult your veterinarian.
Have a question not answered here? Contact us.