Other facts from our historical weather data: Does Monticello have a dry season? Yes, the months of April and June are very dry. Which is the warmest month in Monticello? July has an average maximum temperature of 29°C (84°F) and is the warmest month of the year. Which is the coldest month in Monticello? The coldest month is January with an average maximum temperature of 2°C (36°F). Which is the wettest month in Monticello? December tops the wettest month list with 53mm (2.1 in) of rainfall. Which is the driest month in Monticello? June is the driest month with 14mm (0.6 in) of precipitation. No idea where to travel to this year? We have a tool that recommends destinations based on your ideal conditions. Find out where to go with our weather planner.