anyone?

The highest it will be is the low 70s. Out on the water, esp at night can be a good deal colder. Bring shorts if you want but unlikely to get much use out of them unless you are quite hardy.

And I have never been to europe for more than 2 or 3 days without running into rain (except in southern Spain).

Caveat: with weather anything is possible- but the above is the average.

You are going to Berlin, Germany on this cruise? Do you mean Tallinn?

Even though the temps in these places might be in the low 70s during the day, the cruise itself will be cooler, especially in the evenings and mornings, before you dock for the day.

We took an overnight cruise from Helsinki to St. Petes, St. Pete's to Helsinki and Tallinn to Stockholm. The wind coming off the water, especially at the front of the ship, can be bone chilling at times, and you don't want to be trapped inside because you are cold.

I never travel without a very tiny umbrella. Always better to have one than not. I would also bring a light wind/rain breaker jacket with a hood that you can throw on anytime. One that can fold up small and be stuffed in your day pack.

Other than that I would bring an assortment of layers: mostly moderate weather clothes but a couple long sleeve, long pants. Bring sturdy shoes as there are a lot of cobblestone streets in these towns.