Considering a trip of about 3 weeks to a month's duration in Europe. Flying into and out of Frankfurt. Will stay a few days each in Frankfurt, Berlin, Prague, and Budapest. Traveling by train from Frankfurt to Berlin then to Prague, then to Budapest. Returning from Budapest to Frankfurt by plane as it seems like a long train trip between these two cities.
Since my wife and I are flexible, due to retirement, we can go any time of the year. We are looking at late April or early May. How will the weather be in these cities at those times? Unfortunately, we can't come over in the summer months because we are using frequent flyer miles and it takes much fewer miles to fly before the summer months. Are the trains crowded during April and May? How about those particular cities?