Weather will likely play an important role when you plan your trip to Okawa, but bear in mind that cheaper options are usually available when the weather isn't as good. 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 8°C. The rainiest months in Okawa are June, July, August and May, with each month seeing an average of 330 mm of rainfall.