Europe's weather can vary from country to country depending on the season. Between the months of November and March, parts of north and central Europe can be very cold, whilst the Mediterranean countries remain mild.
The months around Christmas are a magical time to visit Central and Eastern Europe, with traditional Christmas markets and New Years Eve celebrations taking over.
Visit Turkey, Croatia, Greece, Italy and Spain in the spring summer months to make the most of the beautiful beaches and perfect weather... altough you're likely to find warm weather and sunshine in most parts of the continent between May and September.
Prices tend to be highest in Europe at Christmas, Easter and during the summer vacation. Travel during off peak times to save yourself money on accommodation and trips.
If you're departing from Belgium, France or the Netherlands, you might also find it more worthwile to book yourself on the Eurostar and travel directly by train from St Pancras International. From there, you could start your Interrailing trip with an Interrail pass. Head into an STA Travel store to enquire or book.
As a U.S. resident, you'll be granted a tourist visa upon arrival in all European countries, so there is no need to apply for one in advance. In most countries, these visas can last you up to 90 days within any 180 day period, but in the United Kingdom, you can stay for up to six months.