Other facts from our historical weather data: Which months have the greatest rainfall in Rhiw? Most rainfall (rainy season) is seen in October, November and December. Which is the warmest month in Rhiw? August has an average maximum temperature of 18°C (64°F) and is the warmest month of the year. Which is the coldest month in Rhiw? The coldest month is February with an average maximum temperature of 9°C (48°F). Which is the wettest month in Rhiw? November tops the wettest month list with 189mm (7.4 in) of rainfall. Which is the driest month in Rhiw? May is the driest month with 81mm (3.2 in) of precipitation. Which is the sunniest month in Rhiw? May is the sunniest month with an average of 169 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.