In terms of precipitation, rainfall in Rabaul ranges from 3.5 - 9.8 inches per month. March is typically the wettest month, when rainfall can reach 9.8 in. September is typically the driest time to visit Rabaul when rainfall is around 3.5 in.
If weather is an important factor for your trip to Rabaul, 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 80.6 F. Travelers looking to avoid the cold should look outside of July, when temperatures are typically at their lowest (around 78.8 F).