Do horses need blankets in the rain?

Bymuntaseer

Sometimes, and it is the condition that matters most — but a rug is the second-best answer to rain and the wrong rug is worse than none.

Do horses need blankets in the rain?

Rain moves a horse’s comfort threshold further than cold does, which is the part that surprises people.

A dry unclipped horse in ordinary turnout is comfortable down to about 18 °F (-8 °C). Nebraska’s table puts a horse with a soaked coat at 60 °F (16 °C) — a swing of 43 °F (23.6 °C) on the same animal.

The mechanism is simple. A horse stays warm by fluffing its coat to trap a layer of still air, and wet hair lies flat, so the trapped layer is gone.

That is why a mild wet day can be harder on a horse than a cold dry one, and why the answer here is not the same as the answer to how cold it is.

What the evidence says, from three directions

This is one of the few questions in horse care where independent lines of evidence agree without being fitted to each other.

In a survey of 1,450 North American horse owners, exposure to precipitation was the single most frequently given reason for rugging at all, chosen by 78% of those who blanket.

In Norway, horses trained to ask for a rug with symbols were more likely to want one as precipitation increased, and less likely in sunshine. Nobody told them what to prefer.

And the largest review of horses in cold climates concludes that the combination of cold rain and wind is a very demanding weather type, “not just very low ambient temperatures”.

Owners, horses and researchers all pointing at the same weather is about as settled as this subject gets.

Should I blanket my horse in the rain, or not?

Here is the same horse on the same day, with only the weather and the shelter changing.

The same unclipped horse on the same 45 °F (7 °C) day, generated by the blanket weight calculator.
Conditions What it feels like Rug
Dry, sheltered 45 °F (7 °C) Nothing
Dry, open field 37 °F (3 °C) Nothing
Rain, but a shed it can use 45 °F (7 °C) Nothing
Rain, open field 37 °F (3 °C) 17 g

Two things fall out of that table. Rain in an open field takes an unclipped horse from needing nothing to needing 17 g.

And a shed it can actually use takes the whole problem away, because a horse that can get dry is not a wet horse for long.

A stable rug in the rain is worse than nothing

This is the one genuinely dangerous mistake on this page, and every extension source states it plainly.

A stable rug is not waterproof.

Turned out in rain it soaks up water and holds it against the horse’s skin, and Georgia’s extension service says the result is a horse colder than it would have been with nothing on at all.

Colorado State says the same: a rug that is not waterproof “will quickly become saturated, making your horse cold — the opposite of the desired effect”.

So the rule is absolute. If the horse is going out and there is any chance of rain, the rug is waterproof or it does not go on.

The other half of that rule is that a rug goes on a clean, dry horse. Putting a waterproof rug over a coat that is already soaked traps the water underneath.

What to put on: a sheet beats a blanket

In rain that is not especially cold, the useful thing about a rug is the shell rather than the stuffing.

The one study that measured fill weights against skin temperature found the largest single step was from bare to a turnout sheet with no fill in it at all.

It beat the step from that sheet up to 200 g, and it was roughly four times the step from 200 g to 400 g.

A waterproof turnout sheet is therefore the right answer to a mild wet day, and reaching for a heavy blanket instead is a good way to produce a sweating horse under a waterproof shell.

Cold rain is a different matter and does want fill as well as waterproofing. The blanket weight calculator will separate the two for your own horse and conditions.

A shelter beats a rug, and the horses proved it

Seventeen horses were given a full-neck rug and then a free choice between an open paddock, a heated shelter and an unheated one.

They still used the shelters. Rugged horses were inside for 20.6% of observations overall, and 39.7% on days with rain and wind against 11.8% on days that were merely windy.

The researchers’ conclusion was that rugs “reduced the impact of inclement weather, but did not make the shelter redundant”.

That cuts both ways, and it is worth being honest about the second edge. A shelter is only a shelter while the horse is standing in it, so a single doorway that one horse guards is not shelter for the herd.

In the same North American survey, having somewhere to get out of the weather was the commonest reason people gave for not rugging — chosen by 50% of those who leave their horses bare.

Rain scald, and the mud on the legs

The other reason people rug in the rain is skin rather than temperature. Prolonged wet softens the skin and lets bacteria in, which is rain scald along the back and quarters and mud fever down the legs.

A waterproof rug does help with the back. It does nothing for the legs, which are the part standing in the mud.

It can also make matters worse if it is not breathable, because a horse damp underneath a sealed rug is in exactly the conditions rain scald likes.

Worth knowing rather than worth panicking about: a horse in a field that drains, with somewhere dry to stand, mostly does not get either.

When to leave a wet horse alone

A horse in full winter coat, in a mild shower, with a hedge to stand behind, is not in trouble and does not need anything.

Watch what the rain is actually doing. Water beading on the surface of the coat and running off means the coat is still working; water penetrating to the skin means it is not.

Snow is a separate case and a much easier one. Dry snow sitting unmelted on a horse’s back is a sign the coat is insulating so well that no body heat is reaching the surface.

Common questions about horses and rain

Do you leave horse blankets on in the rain?

Yes, if it is a waterproof turnout rug and it went on a dry horse — taking it off part way through is worse than leaving it. No, if it is a stable rug, in which case it should not have gone out in the first place.

Check underneath afterwards: a rug that has stopped being waterproof leaves the horse damp and needs re-proofing.

Do horses like being rained on?

Asked directly, they preferred a rug as precipitation increased and preferred none in sunshine.

That is not the same as hating rain — horses tolerate it comfortably when they are dry underneath and have a windbreak — but they do consistently choose to avoid the cold-wet-windy combination.

How long can a horse stay out in the rain?

Indefinitely in mild rain with a full coat, shelter and enough forage. The clock starts when the coat is soaked through rather than beading, and it runs much faster if there is wind with it.

A horse that can get under a roof when it chooses can stay out all winter.

When to blanket a horse in the rain?

When the horse is clipped, when it cannot get out of the weather, or when the rain is cold and windy rather than mild.

For a full-coated horse with a shed at 45 °F (7 °C), the answer is nothing at all — the same horse in an open field in the same rain works out at 17 g.

Is a rain sheet enough in winter?

Often, and more often than people expect.

In the one study that measured it, a fill-free turnout sheet gained more skin temperature over a bare horse than doubling the fill from 200 g to 400 g did.

In genuinely cold rain you want fill as well, but the waterproof shell is doing most of the work.

Should I bring my horse in when it rains?

Only if it is going to be genuinely wet and cold with no escape from it.

Bringing a horse in costs it turnout, movement and grazing, all of which matter — a run-in shed the horse can use as it chooses is a better answer than a stable it is shut into.

What is rain scald and does a blanket prevent it?

Rain scald is a bacterial skin infection along the back and quarters that follows prolonged soaking.

A waterproof, breathable rug reduces the risk on the covered area, but a rug that has lost its proofing or does not breathe makes it more likely, not less.

It does nothing at all for the legs.

Can I put a blanket on a wet horse?

Not a waterproof one, because you would be sealing the water in. If the horse must be covered while wet, a cooler or a wicking layer under a breathable rug lets the moisture out.

Otherwise let it dry, which under shelter takes a couple of hours.

Related calculators and guides

Where these figures come from

Every figure on this page is published and cited. Where sources disagree we take the more conservative one and say so.

Our full approach is set out in how we source our numbers.