Yeah, 5 mph is barely a breeze. Barely will move a flag. I couldn't fly my micro RC airplane in 5 mph winds and I would see it being tossed around everywhere, but couldn't even feel the wind.

10 mph winds you will feel. 15 mph wind will begin to affect you. 20 mph wind will start to hamper your ability to go forward. 25 will seriously put a stop to your forward movement.

I don't encounter wind that will slow me down to working my tail off downhill just trying to maintain 8 mph very often. That really sucks. I'd put 20 mph wind as really sucks and 15 mph wind as sucks but easily doable.

Rain is the same. There is rain that is no problem, then there is rain that really sucks. I don't have a problem in a slight drizzle, but if it's actually raining and getting the ground wet, I don't ride.