Planning for the weather is a good way to make your trip to Arauco relaxing and enjoyable, especially when you're splurging. The hottest months are usually January and February, with an average temperature of 18°C, while the coldest months are July and August, with an average of 10°C. The rainiest months in Arauco are June, August, July and May, with each month seeing an average of 178 mm of rainfall.