The busy season in Trier runs from May through September.  This is the time when the tourist information office ( http://www.tripadvisor.com/Travel-g18... ) is open the longest hours and runs the most tours and it is also the time when attractions and accommodations are likely to fill up.  For this reason, it is both a wonderful and a terrible time to go, depending upon one’s travel style.  Visitors who want to avoid the crowds but still see all there is to see in the area should aim for early May or early October as the best time to take a trip to Trier.

In terms of weather, these two months are also good months to go, although October can start to get a bit chilly.  The hottest months of the year are July and August, when the average high temperature is in the low eighties.  By October, this average high has dropped nearly twenty degrees and the average low temperature is down below fifty.  The coldest month of the year is January when temperatures are in the teens.  Only fans of quite cold weather should head to the area during this time.

Visitors should know that there is usually five to ten inches of rainfall in Trier during any given month.   July and December are the rainiest months and March is usually the driest month, although rainfall varies.