The predominant wind along the Elberadweg is a north-westerly wind. Therefore, it is generally best to cycle upstream. The difference in steepness is negligible. See also the following tip: Upstream or downstream?.
Generally, most cyclists prefer not to ride for long in the rain. However, the right clothing can be helpful.
A cape or poncho has considerable benefits compared to waterproof jackets and trousers, as it won’t cause as much sweating. However, the surface area is larger for the wind. It makes sense to have a poncho with a well-fitting hood with clear sections at eye level so you don’t lose your side vision. The poncho is placed over the handlebars and secured with sewn-on bands. The back should have two bands, which you can tie around the body to reduce the effects of the wind.
Clothing made from microfibres dries very quickly. Shoes, and therefore your feet, stay cold and wet for much longer. Plastic bags or galoshes can help. Watch out if you have cages or click-on pedals!
Gloves should be windproof to protect from the cold. Fleece lined base layers are very useful - it might sound obvious but your bladder and kidneys etc are very sensitive. Thick socks with faux fur and/or windstoppers are expensive but very useful. Scarves are versatile, as they can be used on your head, ears or neck (prevents a stiff neck after long journeys).
Coverage is more effective than any sunblock. A loose long-sleeved shirt can also protect against mosquito bites - you can even fasten just the top button if you’re wearing a jersey underneath to offer coverage for your arms. Visors and mesh baseball caps (mesh for optimal ventilation) should be worn low, and glasses should be worn to protect the eyes.