Just curious...I have been following the weather the last couple of weeks and I have noticed a lot of rain. I am not familiar with Germany's weather. When it is showing rain, does it rain all day or just off and on throughout the day like summer showers? Is the day a complete washout when it rains there in the summer? Thanks!

Everything is possible.

And only very little rain in Munich during the last month. It rained a lot further north it seems.

When it rains, it's usually off and on in Summer. And quite a lot too And no, you don't need A/C.

Completely depends on where you are. I've been checking the weather too and seeing mostly rain for the Heidelberg area at least. A complete washout would depend on what your plans for the day are. City/town site seeing isn't horrible, but if you're going for the view.. .then sure, it could be a pain...

Most of my colleagues would beg to differ regarding AC. Doesn't bother me, but the last few summers it's been over 90 during the last few weeks in July, and not all that much relief at night.

Well, as posted before, you must be American if you need A/C. . In my office: "Oh, it's quite warm today, isn't it?", "Yes, actually it is, I'll open the window". "Anything important today?".
It's a non issue. Rain is a subject to talk about, it always comes on weekends, never during the week!

From a statistical point of view, the Northeast of Germany gets the most sun and usually has dry hot summers and dry cold winters. Berlin is also in this area, and you can easily have 3-4 weeks of temperatures in the 90s and not cooling off much at night in summer.

The Southwestern parts (Black Forest, upper Rhine Valley) is also warmer than the rest.
The Northern and Central parts are usually bit cooler.
The Cologne / Frankfurt area (where the most popular part of the Rhine valley is located) often has a quite nasty humid and warm climate in summer. That is definetely one part of Germany where A/C makes lots of sense when you search for a hotel for July/August.

I am not too concerned about heat since I live in Houston, TX! I was just wondering if rain would affect doing a lot of outdoor acitvities or if it just came down in showers. Here in Houston in the summer we get rain most days but it isn't all day long. We have heat everyday though! But, we do have air conditioning to save us!

Most parts of Germany have an atlantic maritime climate, not only the coastal areas.
This makes the weather more unpredictable, and you can get weeks of sunshine as well as a daily mix of rain and sunshine or 1-2 days of continous rain.

The North (the coastal region) gets more and often continous rain, so do the lower mountains which you will find in Central Germany.

In other parts more than 1 or 2 days of continous rain are uncommon in summer.

Only the Northeast and Easternmost regions of Germany get dry continental climate with less overall rain.

>I was just wondering if rain would affect doing a lot of outdoor acitvities

IF you get a continous rain, it will be a light drizzle against which an umbrella will be enough. It is not a monsoon area after all
Most summer rain comes in showers though.