Tonight’s low, the wind, rain or dry, his coat and his shelter — and two answers kept apart on purpose: whether the university extension services say he needs a blanket at all, and which weight a blanket maker’s chart suggests if he wears one.
Does he need a blanket tonight?
Probably not
What each source says for his coat
Penn State’s reasons to blanket, tonight
If he wears one — Schneider’s weight chart
These are published guidelines, not a reading of your horse. The horse in front of you is the last word: if he is shivering, tucked up or his coat has gone wet and flat, he is cold, and if he is sweating under a blanket, it is too warm. A blanket never replaces shelter, hay and water.
Guidelines checked 2026-09-25.
Quick answer: a healthy adult horse with a full, dry winter coat and somewhere to get out of the wind usually does not need a blanket until the temperature falls to somewhere between 5 °F and 18 °F, depending on which extension service you read and how used to cold winters he is. Wet changes everything. A wet coat stops insulating, and Rutgers puts the line at about 59 °F for a wet, clipped or summer-coated horse. A clipped horse usually needs one below about 50–60 °F. A foal, a senior or a thin horse needs one sooner.
How to use it
Put in tonight’s low, the wind if there is any, whether he will be out in rain or sleet, his coat and whether he can get into a stall or run-in shed. You get two answers, kept apart on purpose. The first is whether the extension services say he needs a blanket at all. The second is which weight Schneider’s blanket chart suggests if he wears one. The first answer matters more. The most common blanketing mistake is a blanket on a horse that never needed one.
Why the experts give different temperatures
The number every blanketing chart is really about is the horse’s lower critical temperature: the point below which he starts spending extra energy just to stay warm. It is not one number. The University of Georgia’s extension puts it around 5 °F for a horse in good condition that is used to cold, 18 °F for one from a milder climate, and 40 °F with only a summer coat. Rutgers quotes 18 °F for a full, dry winter coat and 59 °F once the animal is wet, clipped or in a summer coat. Those figures come from beef cattle studies, which Rutgers says are “likely similar in horses”. Penn State gives the reasons to blanket rather than a temperature: no shelter below 5 °F or a 5 °F wind chill, wet weather, a clip, a very young or very old horse, one that has not adjusted to the cold, or a body condition score of 3 or less.
They are not contradicting each other so much as describing different horses. That is why the chart shows every line that applies to yours and says whether tonight is above or below each one.
Wet is worse than cold
A winter coat works by trapping air. Rain flattens it, mud fills it, and the insulation is gone. Penn State notes that as little as a tenth of an inch of rain can cause cold stress. Snow sitting on a horse’s back is a good sign: it means the heat is staying in under the coat. Never put a blanket on a wet horse. Dry him first, with a cooler if you have one, then blanket.
If you do blanket, which weight?
Blanket weights are measured in grams of fill. Schneider’s publishes the chart this tool reads. A turnout sheet has no fill. A lightweight has 80–180 g, from about 30–50 °F for a full-coated horse and 40–60 °F for a clipped one. A medium weight has 200–300 g, a heavyweight 380–440 g, and a 500 g stable blanket is for below 15–20 °F. Schneider’s own ranges overlap, and it calls them “starting points”. Check under the blanket after an hour. If he is damp or warm there, go lighter.
Feed him for the cold, too
Rutgers’ rule of thumb is that a horse needs about 1% more energy for each degree below his critical temperature. The warmth comes from fermenting fibre in his gut, so the cold-weather answer is more hay, not more grain.