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In terms of precipitation, rainfall in Rotterdam ranges from 1.7 - 3.3 inches per month. October is typically the wettest month, when rainfall can reach 3.3 in. February is typically the driest time to visit Rotterdam when rainfall is around 1.7 in.
If weather is an important factor for your trip to Rotterdam, use this chart to help with planning. For those seeking warmer temperatures, July 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 37.4 F).