In terms of precipitation, rainfall in Blenheim ranges from 1.6 - 2.8 inches per month. May is typically the wettest month, when rainfall can reach 2.8 in. March is typically the driest time to visit Blenheim when rainfall is around 1.6 in.
If weather is an important factor for your trip to Blenheim, 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 64.4 F. Travelers looking to avoid the cold should look outside of July, when temperatures are typically at their lowest (around 44.6 F).