Weather is probably a major factor when you plan your trip to Lago Ranco, but bear in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually January and February, with an average temperature of 13°C, while the coldest months are August and July, with an average of 7°C. The rainiest months in Lago Ranco are June, August, July and May, with each month seeing an average of 400 mm of rainfall.