Manado is the capital. It is well known for mainly three things:

1. Its variety of spicy-but-tasty grilled foods (i.e. Ayam Rica Bakar = Grilled Spicy Chicken, or freshly caught deep-sea fish grilled right in front of you).
   
2. World class diving / snorkeling destination, which is Bunaken Island.
3. Tarsius, the world's smallest monkey, at the lush mountains of Dua Saudara Nature Reserve on Tangkoko Mountain.

The temperature and weather does not vary widely during a course of a year (70-85 degrees Fahrenheit).  But the best time to visit in terms of fun activities and celebrations, would be between Christmas and New Year's Eve.  During this special time of the year, there is a great abundance of heavenly tropical fruits such as mangoes (dozens different kinds), durians (spiky tasty fruit that you will either hate or love), duku, manggis (in the Western world heavily marketed as the cure-all Mangosteen), and many more. 

Aside from the fruits, there are all kinds of end of the year celebrations going on from the villages (i.e. Minawerot villages of Kauditan 1-2, Kawiley, Treman, Kaima, Karegesan, Kaasar, Lembean, Paslaten, Tumalungtung), to the downtown area (Boulevard). 

Most people speak broken English although most understands very well.  A Seventh-Day Adventist Church Klabat University in Airmadidi has been providing rigorous English courses for students by native-speaking American / Australian teachers for decades.