Today at the barn.

Add the temperature in Fahrenheit to the relative humidity as a percentage. Under about 130 is comfortable for work. Between 130 and 150 the horse's cooling starts to struggle, particularly if the humidity is more than half the total. Over about 150, University of Minnesota Extension advises against riding, especially for horses not acclimated to heat.

Montana is usually dry, which is why the number here is usually low even on a hot day. That is real, not a bug. Dry heat is genuinely easier on a horse than the same temperature in humidity.

Every daylight hour in the next two days gets scored on heat load, chance of precipitation and wind, and the best run of consecutive hours is what gets shown. It is a rough sort, not a recommendation.

It knows the sky and nothing else. It has never seen your arena, your gate, your footing or your horse, and it does not know that the river trail floods or that your gelding is unrideable on a windy Tuesday. Those you still have to supply.

If the overnight low is at or below freezing you get a reminder to check troughs, heaters and cords before bed. Reduced winter drinking is considered the main predisposing factor for impaction colic, and warming the water raises intake substantially. More in the winter guide.

Flagged when the low is at or below freezing and the following high is above it. That cycle turns churned ground into ruts and then into ice. Treat it as a prompt to go and look, not as a fact about your paddock. Every property drains differently and no forecast knows yours.

Rain flattens a winter coat and destroys its insulation, and wind strips the warm air off the skin. Cold alone is rarely the problem. Cold plus wet plus wind is, and that combination gets flagged separately from temperature.

The number shown is the US EPA Air Quality Index, the same scale used for people. Under 50 is good, 51 to 100 moderate, 101 to 150 unhealthy for sensitive groups, and above that it climbs through unhealthy to hazardous.

There is no horse specific AQI, and that matters. UC Davis notes that research on horses and wildfire smoke is limited, so the human thresholds are the best available guide rather than a standard designed for a 1,100 lb animal breathing far more air than you are. Treat the number as a direction, not a rule.

The practical guidance during smoke: limit strenuous work, keep water in front of them, and give a horse that has had a hard smoke exposure real recovery time before asking for hard work again. If you can smell it and see it, that is enough information to go easy.