Taking the local weather in Ota Onsen into account is an important factor for planning your visit, especially if you plan to spend your trip by the pool. The hottest months are usually August and July, with an average temperature of 20°C, while the coldest months are January and February, with an average of 3°C. The rainiest months in Ota Onsen are June, July, August and September, with each month seeing an average of 357 mm of rainfall.