Other facts from our historical weather data: Which is the warmest month in Hilo? August has an average maximum temperature of 26°C (79°F) and is the warmest month of the year. Which is the coldest month in Hilo? The coldest month is February with an average maximum temperature of 23°C (73°F). Which is the wettest month in Hilo? March tops the wettest month list with 273mm (10.7 in) of rainfall. Which is the driest month in Hilo? June is the driest month with 117mm (4.6 in) of precipitation. Which is the sunniest month in Hilo? June is the sunniest month with an average of 179 hours of sunshine. 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.