Other facts from our historical weather data: When is the rainy season in Nanyuki? Rainy season in Nanyuki occurs in the months of April, May, October and November. Which is the warmest month in Nanyuki? March has an average maximum temperature of 25°C (77°F) and is the warmest month of the year. Which is the coldest month in Nanyuki? The coldest month is January with an average maximum temperature of 21°C (70°F). Which is the wettest month in Nanyuki? April tops the wettest month list with 288mm (11.3 in) of rainfall. Which is the driest month in Nanyuki? September is the driest month with 85mm (3.3 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.