In terms of precipitation, rainfall in Grafton ranges from 1.6 - 4.7 inches per month. January is typically the wettest month, when rainfall can reach 4.7 in. August is typically the driest time to visit Grafton when rainfall is around 1.6 in.
If weather is an important factor for your trip to Grafton, 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 75.2 F. Travelers looking to avoid the cold should look outside of July, when temperatures are typically at their lowest (around 55.4 F).