The Effects of Weather & Climate on Horses

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How Weather & Climate Affects Horses

The seasons in Alberta can impact many aspects of care provided to a horse, particularly nutritional and sheltering needs. The extent to which weather and climate affects care is also influenced by whether the horse is kept outdoors in a pasture or paddock, or indoors part-time in a stable.


Seasonal influences on a horse’s nutritional needs vary, depending on location. If you are located in an area that has very mild seasonal changes, the seasonal influences might be so little that you don’t have to make any changes to a horse’s diet.

On the other hand, if you live in a place that has drastic differences between seasons, the horse’s nutritional needs will be more impacted. Both extreme hot and cold weather can be difficult for horses to handle.

The impact of seasonal changes can depend on where and how the horse is sheltered. For example, a horse kept out on pasture full-time is affected more by seasonal changes than a horse that is stalled part of the time.

Summer and winter are often times when horse owners or caregivers need to adjust a horse’s diet due to seasonal influences on nutritional needs, but spring and fall can also result in challenges, especially if a horse is pastured full-time.

During the early spring, attention should be paid to a horse’s grass intake. The increase in non-structural carbohydrates, starches, and sugars in grasses during the spring can increase the risk of colic and laminitis or founder.

There are different strategies that can be used to control grass consumption in horses.

If horses are housed outdoors 24/7, they will typically adapt naturally to the changes in spring pasture. However, if your horse is housed indoors part-time, it is recommended that you transition your horse by limiting their daily access to pasture.

  • Using this method, your horse is turned out for progressively longer periods of time until they are turned out for the desired amount of time. When the grass reaches approximately 6 inches in height, allow the horse about 1 hour of access to the pasture before housing them in a dry lot or sacrifice paddock. Then, slowly increase their access to the pasture every other day, by about 30-60 minutes. Consider turn out in the early morning, when non-structural carbohydrates in grasses tend to be lower.
  • Horses with metabolic issues require a diet that is low in non-structural carbohydrates and may be best managed on a dry lot with hay as their only forage source. Always consult with a veterinarian when planning the diet of a horse with metabolic issues.

Grass intake can also be controlled by limiting space available to a horse. This can often be easier for owners or caregivers who don’t have time to turn horses in and out every day or for horses that should not have free access to pasture, such as horses with metabolic issues.

“In the foothills of the Rocky Mountains, chinooks are a fact of climate and life. These warm winds, originating as moist, cool Pacific coast winds are blamed and blessed for the havoc and heaven they bestow upon southern Alberta.

Some wonder how chinooks affect their horses, and whether particular care requirements could better support their equine populations in dealing with these seasonal winds. “Generally speaking, horses are quite well adapted for the large temperature swings that can occur in chinooks,” explains Dr. Greg Andrews, equine practitioner at Moore Equine Veterinary Centre in Calgary.

“The three areas that could be affected by temperature swings are the animal getting too cold or too warm, sudden changes in eating and drinking patterns — and these things may result in a potential increase in colic and gastrointestinal upset,” [he added].”

Excerpt obtained from "Chinooks Demand Direct, Hands-on Horse Care", Horses All Magazine, Volume 35, Issue 1. 

During the spring season, horses should be watched carefully for signs of colic or laminitis, or any other problems.

LINK: Use this Colic Risk Rater Healthcare Tool by Equine Guelph to help assess your horse’s risk of colic.

Introduce horses gradually to pasture if they are kept indoors part-time. Keep horses in a smaller pasture to limit access to grass if they cannot be time-restricted during the day. For horses more prone to laminitis or colic, or have metabolic issues, the horse should be kept in smaller pasture or dry lot to minimize access to grasses.

With either method, horses should be closely monitored at least daily to ensure that they are not showing signs of problems. Horses that are particularly prone to colic or laminitis can also wear a grazing muzzle to further reduce their intake of grass. Ensure the grazing muzzle is properly fitted and the grass is at least 6 inches in height so the horse can access the grass through the muzzle.

LINK: Refer to this info sheet by Equine Guelph on grazing muzzles for more information.

Seasonal influences on horse nutrition are varied and impacted greatly by your location and environment.

LINK: Watch this Equine Guelph video [27.20 minutes] about how you can reduce spring colic with safe pasture introduction methods with Don Kapper, an equine nutritionist.


Horses can live outdoors comfortably in colder temperatures, as long as they are given time to acclimatize and are provided with plenty of hay, water and an adequate shelter designed to protect against inclement conditions.

Shelter options for three basic wintertime weather conditions are described below:

Dry and windy: Strong winds that cut across the land can be even more chilling to unprotected horses than frozen precipitation. A windbreak fence with 20 percent porosity, which refers to the spaces within solid material, allows some wind to filter through and provides better downwind protection than a solid windbreak. If winds are variable, a three-section windbreak with walls arranged around a centre post like wheel spokes provides different options for protection. In areas of particularly strong winds, these sheltering walls need some openings to let air pass through; solid structures are more likely to be toppled by gusts.

Rainy and windy: Cold rain driven by strong wind can be miserable for horses. A simple three-sided, roofed structure offers adequate protection in these conditions. The structure should be located on a well-drained location with its back wall to the prevailing wind, and have a roofline that diverts rain runoff away from the entrance where horse traffic makes some mud inevitable. Have the floor graded with a slight slope to the sides and a slight crowning at the entrance to reduce the formation of mud inside the shed. For most satisfactory footing during the worst of the rainy season, invest in underground drainage and stone dust or aggregate surface materials during construction.

Snowy and very cold: If winter regularly brings snowstorms and consistent subfreezing daytime temperatures, turned-out horses can be safe and comfortable in a shed, but the construction needs to be solid and strong enough to stand up to heavy snow accumulation. Roof slope and strength are important. A steep pitch away from the entrance “shrugs off” snow accumulation where horses won’t be standing and reduces chances that the entrance will be blocked.

If properly sited with the opening facing the most protected direction (often south), a three-sided shed usually provides sufficient shelter, but in extra-cold areas, partial enclosure of the fourth side makes the interior cozier. Grade and maintain the shed floor to reduce mud formation, and bed it to make a dry, warm place out of the snow.

Natural shelters, including trees and bush, also provide excellent sheltering options for most horses.

Information adapted with permission from "Winter Shelter for Pastured Horses" by the Editors of Equus Magazine.
LINK: Refer to the next topic "The Effects of Land, Soil & Water on Horses" to learn more about how environmental factors can affect living spaces for horses.


Climate impacts to horses are exacerbated by climate change. Climate models for Canada suggest drier hotter summers, increased winter and spring precipitation which can result in flooding and colder winters. These weather patterns also impact hay and grain prices. Drought conditions and extreme weather drive feed prices up, which is something horse owners need to be aware of.

Climate change also increases the risk of forest fires; therefore emergency preparedness is very important for horse owners. Warmer weather also impacts disease transmission – many pathogens that carry infectious diseases prefer warm climates. For instance, most cases of West Nile Virus in Canada, have been found in horses in August and September. Warmer weather might extend the season of the mosquito that transmits this virus, which could result in more cases.

Horse owners need to be aware of the impacts that climate might have on their horses, and be prepared to keep them safe and healthy during more extreme weather conditions.

Photo Credit: Farell Albert-Puurveen

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