Hoya bicknellii was discovered in Matutinao, Badian, Cebu in the Philippines. “Cebu’s temperatures can reach a high of 36 °C (97 °F) from March to May, and as low as 18 °C (64 °F) in the mountains during the wet season. The average temperature is around 24 to 34 °C (75 to 93 °F), and does not fluctuate much except during the month of May, which is the hottest month. Cebu averages 70–80% humidity.” (Quote taken from Wikipedia) When you see these temperatures and humidity readings it is truly remarkable that we can grow these plants at all in the house.