The last time I was traveling to Germany in rainy weather, I did a travel photography course from my favorite National Geographic photographer, Joel Sartore, before flying out (the course can be ordered from National Geographic). Joel is a brilliant photographer and I have also gone through his Fundamentals of Photography Course (also from National Geographic) several times!
On shooting people in cloudy weather against rich green backgrounds, Joel advised on the subject wearing white or a bright color, to really make it pop out in the picture.
I was in Baden Baden and it had rained all night. Everything was a lush green. Despite a train to catch, I quickly ran to the nearby Goenneranlage, a historic park and botanical garden, where I clicked the pictures for this post. My white fleece jacket is from Polo Ralph Lauren which besides making great pictures in rainy weather, is also a great travel piece to wear in-flight and otherwise! Also, the bright red umbrella really stands out! I took my own pictures with a tripod.