In terms of precipitation, rainfall in Groningen ranges from 1.7 - 3.1 inches per month. November is typically the wettest month, when rainfall can reach 3.1 in. April is typically the driest time to visit Groningen when rainfall is around 1.7 in.
If weather is an important factor for your trip to Groningen, use this chart to help with planning. For those seeking warmer temperatures, August is the ideal time of year to visit, when temperatures reach an average of 62.6 F. Travelers looking to avoid the cold should look outside of January, when temperatures are typically at their lowest (around 35.6 F).