Planning for the weather is a good way to make your trip to Chillan relaxing and enjoyable, especially when you're splurging. The hottest months are usually January and February with an average temp of 68°F, while the coldest months are July and August with an average of 48°F. The rainiest months in Chillan are June, August, July, and May, with each month seeing an average of 9 inches of rainfall.