In terms of precipitation, rainfall in Río Grande ranges from 0.6 - 1.5 inches per month. May is typically the wettest month, when rainfall can reach 1.5 in. September is typically the driest time to visit Río Grande when rainfall is around 0.6 in.
If weather is an important factor for your trip to Río Grande, 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 51.8 F. Travelers looking to avoid the cold should look outside of June, when temperatures are typically at their lowest (around 32.0 F).