Planning for the weather is an important factor for making your trip to Minami Oosumi a success, especially when you're splurging. The hottest months are usually August and July, with an average temperature of 25°C, while the coldest months are January and February, with an average of 11°C. The rainiest months in Minami Oosumi are June, July, May and September, with each month seeing an average of 388 mm of rainfall.