May Weather in Germany

It's hard to say because it can vary so much. On a few trips to different parts of Germany in May, I have gone back and forth between being comfortable in lightweight capris and short sleeves, and needing a jacket. I would suggest looking at a weather website for the average temperatures for the towns you will be staying in, and then packing for some layers. You can also probably count on some sun and some rain.

What will the weather be like in Watertown, WI in May? The answer is--who knows? I have been in Germany in March when we sat outside all day, every day, in bright sunshine and warm temperatures. I even got a litttle suntan. The same year I was there in July and there was not one day on which I did not need a sweater and sometimes even a jacket on top of that.
Pack light, but be prepared for anything.

The others hit it. The only solid prediction you can probably make is that temperatures probably won't feel like winter (except, perhaps, at very high altitude in the Alps). Even within a relatively short period of time, temperatures can fluctuate wildly. Two weeks ago, we were roasting during the day, now I'm wearing a sweater as I type this. Also, there can be large variations in weather conditions within the country at the same time. At least three distinct major climate zones overlap within the country, with the warmest areas usually being in the SW (the wide upper Rhine valley), and the coldest in the SE (Upper Bavaria).

A number of years ago my husband and I drove from Paris to Frankfurt/Oder on the border of Poland to visit friends. Because it was the month of May asparagus was on every restaurant menu, in fact the restaurants had separate menus for their asparagus offerings, the "Spargel Menu". I was in heaven and ate asparagus everyday! At the public market in Frankfurt/Oder it was interesting to see that green asparagus (so common here, with the white kind rare and expensive) was much more costly than the white. Sorry, this has nothing to do with the weather, does it!

I have gone in May a few times and had great weather, but I tend to be lucky with the weather when I am traveling. I also spent a few weeks there in April and it was beautiful and a friend who lives in Germany went to Turkey in April and while it was really warm in Germany, she froze in Istanbul... so who knows? But, I would rather have a few layers in May to keep warm then to swelter in the summer amidst tons of tourists.

All we know for sure is that the weather is very unpredictable! My sister and her family are in Paris right now and it is rather cold and rainy almost every day. It should be spring like if not summer weather, in most of Europe.
Take clothes for all kinds of weather including layering, to be safe. Happy Travels!

Plan for rain & cooler temps & enjoy it if you get sunny & warm. Layers are key.

One year, I was in Germany in the month May. In the first week in May, at the castle Marksburg at Braubach (at the Rhine River, east of Koblenz), in the afternoon the sunlight was very hot, causing pain to my head, and sunburn at the back of my neck.

Try http://www.weatherbase.com/
This is what I use. Just plug in the cities you're going to visit and see the results.