In terms of precipitation, rainfall in Rosario ranges from 1.2 - 5.9 inches per month. March is typically the wettest month, when rainfall can reach 5.9 in. July is typically the driest time to visit Rosario when rainfall is around 1.2 in.
If weather is an important factor for your trip to Rosario, use this chart to help with planning. For those seeking warmer temperatures, January is the ideal time of year to visit, when temperatures reach an average of 77.0 F. Travelers looking to avoid the cold should look outside of June, when temperatures are typically at their lowest (around 50.0 F).