In my experience, when pasturing horses 24/7, the less I interfere the better (ie) blanketing, clipping and locking them in. The horses that turn out in nice weather and stable at night on my farm work/show all year so they are clipped and obviously require blanketing. As Jane mentioned, if a horse wears a blanket out in the rain, it needs to be changed to dry otherwise the horse will be cold. Most of my broodmares are happy outside 24/7 365 and they are not blanketed and they have access to a shelter more than big enough for everyone , so no-one gets shoved out in the cold/rain. I have a 21 year old mare who exhibits signs of being cold, so she wears a turnout and I bring her in when it rains. In my personal opinion (this is how I was brought up with horses) my trainer taught us that several common sense rules applied: If you blanket the horse, you keep him dry and stable him because you intent to work him all winter, if you leave him out 24/7, you never blanket or clip as he does not need it, and if you didn't blanket as it was getting cold, you didn't all winter as the horse grew a hair coat and wouldn't need a blanket and dressing him would make him sweat and chill. Now remember, when I was a kid learning horses, waterproof blankets were not widely used and were hardly waterproof so a horse in a blanket in the rain was better off naked ( with a long coat) as a wet rug does no good. A clipped horse doen't belong outside Without a rug. Extenuating circumstances apply too, old or ill or skinny horses and horses moved to a cold climate need extra attention. Nowadays, there are a lot of options for waterproof turnouts, but as people have mentioned, they do need swapped out regularly which means you have a lot more work. Plus, most of the waterproof turnouts I've used still let the horse get wet at the neck and shoulder, thus limiting their effectiveness. . I think that too many people over think it and treat their horses like people, doing more harm than good (ie) it's cold out, I need a coat, so my horse needs a coat or I go inside at night so my horse must go in at night and so on. Everyone does things differently and that's tbe beauty of the horse world, you need to do what's best for you and your horses. In my opinion, your horses will be fine with 24/7 outside turnout as long as they have access to shelter. If you have been locking them in at night, they may take some time to get comfortable being left out. I have had horses refuse to use a run-in shelter and instead pace the fence or stand at the gate in the rain shivering because they were ALWAYS stabled and felt more comfortable that way. In order to teach them to stay out, I begin the transition in the summer months when it's warm and I feed them in the run-in to acclimate them to it. sometimes, I find it is easier in the event of ice storms and blizzard noreaster storms, to stable everyone so I'm not trudging through two feet or snow or breaking my tail falling on ice sheets to water and feed horses. But, once the ice/snow is over, I've plowed and sanded the yard, everyone is happy to go back out.