Upon arrival and disembarking from the plane, one immediately notices the sudden rush of warm, wet air. Indonesia is a warm place. It has no spring, summer, fall, or winter, just two seasons: rainy and dry, both of which are relative (it still rains during the dry season, it just rains less). While there is significant regional variation, in most of the country (including Java and Bali) the dry season is April to October, while the wet season is November to March.

In highland cities/resort the temperature is somewhat cooler and many people from outside these cities are wearing jackets: Bandung, Puncak, Tangkuban Perahu, Telaga Remis (Kuningan), Buana Jaya, Megamendung (Bogor), Situ Gunung (Sukabumi), Sampireun (Garut) in West Java, Curug Gendang (Carita) in Banten, Mt. Sumbing, Baturaden, Kaliori (Banyumas), Kopeng, Dieng, Tawangmangu, Sumber Semen (Rembang), Colo, Kajar and Rahtawu (Kudus), Wadaslintang Dam (Kebumen), Sayuran (Blora), Tahura, Grojogan Sewu (Solo), Tambi Plantation (Wonosobo) in Central Java, Kaliurang in Jogyakarta, Mt. Bromo, Mt. Ijen, Mt. Kelud, Blokagung Dam (Banyuwangi), Selorejo, Malang in East Java, Bunut Bolong, Palasari Dam in Bali, Brastagi in North Sumatra, Ranau Lake in South Sumatra, Tidal Forest of Mokoh River, Pangkalan Lesung in Riau, Pagar Alam in Bengkulu, Pangkalan Buton (Ketapang) in West Kalimantan, Bukit Kasih, Tomohon in North Sulawesi, Boalemo in Gorontalo, Tana Toraja, Soppeng, Malino, Katun Valley (Palopo) in South Sulawesi, Arfak Mountains, Papua.

In Papua island, there are snow covered peaks: Jayawijaya Mountains: Peak Trikora (Mt. Wilhelmina) - 4730 m. Sudirman Mountains: Peak Jaya (Mt. Carstensz) - 5030 m.