In terms of precipitation, rainfall in Vanimo ranges from 5.0 - 12.6 inches per month. January is typically the wettest month, when rainfall can reach 12.6 in. September is typically the driest time to visit Vanimo when rainfall is around 5.0 in.
If weather is an important factor for your trip to Vanimo, use this chart to help with planning. For those seeking warmer temperatures, April is the ideal time of year to visit, when temperatures reach an average of 82.4 F. Travelers looking to avoid the cold should look outside of January, when temperatures are typically at their lowest (around 80.6 F).