I totally agree with Nainosliw
Wet and hot sucks.
Wet and cold can damage your health.
Wet and an OK temperature with merino is ok.
I wear a Gore windstopper jacket and a merino long sleeve base layer, and that keeps me right come rain or minus temps, for hours or even a day ride, as long as the stops aren’t too long and there is warmth (car, house) at the end of it all. The jacket has zip off arms so I can use it as a gilet when needed. Have fallen onto tarmac on it, no rips. Have worn heavy backpacks with it, no wear. 3 years old now with a fair amount of use, and looks like new.
If I was camping at the end of the day, I’d be thinking of trying to keep dry more, probably by using a waterproof and slowing down, but I don’t have experience of that yet.