WWYD? Horse has full heavy winter coat, it is now 45 and raining, will be up to 60 and still raining by morning. Put on an unlined rain sheet, or no? He could use it now but likely sweating under it by morning. He was out in the rain today and is not currently shivering.
How old and healthy is horse? If young and robust, I’d leave it off. If older and likely to be shivering, I’d put it on.
Is there a run-in he can get into? (I have sheds in my fields but not all the horses are sensible and use them – some stand outside in the rain and shivering, so sheds alone aren’t always the answer!)
Drenching rain or mist? If just misty, I wouldn’t lose sleep over not sheeting him. But more than likely I’d put the sheet on, and just get up a bit earlier than usual to strip off. I don’t think he’ll sweat extensively to where it’d be a problem. A consideration other than being cold is rain rot from having a sodden winter coat.
But bottom line, the consequences for either decision are really minor.
I’d put a sheet on, a steady cold rain is worse than a warm rain or snow. It gets through to the skin and makes the horses shiver. If you take it off in the morning he isn’t going to be sweaty.
I would sheet him. As the above poster said a cold steady rain is a lot worse then snow or warm rain.
As long as it’s overcast and 60 degrees, the sheet is probably fine. Mine sometimes feel warm, but never sweaty. Leaving them on at that temp isn’t my preference, but if we’re in between storms and I know it’s going to rain again overnight, the sheets stay on because I can only get to the barn once a day. If it was sunny out and 60 degrees, I would probably remove the sheets and risk them getting wet overnight. Also not ideal, but they won’t actually die if they get wet 
It started pouring right after I posted that, so I put him in the sheet. It’s the first time I have had to blanket him, but it’s really wet and cold rain is the worst! We’ll see how it looks tomorrow morning.
Now that mine have their full winter coats, I’m not bothering with the rainsheets, and the temps are in the 30’s. They have shelter and hay. I would consider it if it’s pouring rain, but here it’s just been drizzling off and on for the last two days.
Ditto saultgirl. My drafties are quite fluffy. Even in the pouring, cold rain yesterday evening, they ate their warm beet pulp outside with not a single shiver.
They have dry hay in the Hay Hut 24/7 and shelter if they want it. They don’t.
If they were older and couldn’t maintain body weight, I’d sheet them.
[QUOTE=regalace;7923595]
WWYD? Horse has full heavy winter coat, it is now 45 and raining, will be up to 60 and still raining by morning. Put on an unlined rain sheet, or no? He could use it now but likely sweating under it by morning. He was out in the rain today and is not currently shivering.[/QUOTE]
NOPE. 
Takes a lot more weather than that to make them uncomfortable.
rain sheet is the way to go.
Mine are out in light rain now; as they have been for the last few hours. It’s 35F and they are fine.
[QUOTE=saultgirl;7927048]
Mine are out in light rain now; as they have been for the last few hours. It’s 35F and they are fine.[/QUOTE]
Thirty five and light rain with no wind is fine. Driving rain, wind and 35 is a whole 'nother ball game.
