We’ve had some steamy days this week in New England — both hot and humid. Having complained all winter that it was too cold, I feel like I’m whining to complain about the heat now, but there are some days when I can’t bring myself to ride — especially after I’ve cleaned stalls and picked the paddocks.
While it may be uncomfortable to ride when it’s hot, when heat is combined with high humidity (over 75%), it can prevent your horse from humidity combine, it can compromise your horse’s ability to cool himself.
Here’s a formula that can help you assess whether the heat is excessive.
(Temperature + relative humidity) – wind speed = Heat Stress Index
Based on the sum of the numbers, you can get a general sense of how safe it is to ride.
Less than 130: All go-horses can function to cool themselves assuming adequate hydration.
130 – 170: Caution-a horse’s cooling mechanisms can only partially function as intended. Some cooling management procedures will need to be performed.
180 or above: Stop-a horse’s cooling systems cannot and will not function adequately. All cooling procedures will need to be utilized to keep the horse out of serious trouble.
On Tuesday I had a lesson on what was the hottest day so far this summer. It was 93 degrees and 59% humidity with winds blowing at 13 mph. That gives a heat stress index of 139. I was lucky enough to have the last ride of the day, at 6:45 p.m. The sun was already off of the arena and the wind was starting to pick up, so I’m guessing the heat stress index was lower than 130. But it was still HOT and I feel sorry for the folks who rode before me.
Most summer days I try to ride before 8:30 a.m. while it still feels fresh and cool.
Whenever riding in the heat it’s important to also keep in mind your horse’s fitness level (and your own) and whether you will be riding in direct sun. I often just take a light hack in the woods on very hot days even though Freedom is quite fit.
And if you know that you are going to have a hard ride in the heat, you might consider those electrolytes that I wrote about earlier. You don’t want your horse to become dehydrated.