Amber Mountain National Park
Best time of the year is September to November. Rain can occur from time to time particularly in the night. Avoid December to March; the rainy season with a high risk for cyclones.
Amber Mountain has a lush vegetation and offers a rich biodiversity. If possible try to stay there for a night or in Joffreville. It's only 30 km from Diego. In 2012 it was a gravel and bumpy road. You'll definetely see many night active chameleons. We booked our tour in advance and got offered to stay in an old house. The community of the village prepared dinner and breakfast for us. We did a hike on both days and discovered Northern ring tailed Mongoose, Sanford's brown lemurs, Crowned lemurs, Pygmy stump-tailed chameleons even Leaf-tailed geckos and many more. Amber Mountain is also outstanding for birding. If the soil is wet be aware of leeches.