Gede Pangrango is one of the wettest parts of Java with a mean annual rainfall between 3,000 and 4,000 mm and with, even in the four driest consecutive months of the year, still more than 40 rainy days. The wettest season is from October to May, coinciding with the North West moonsoon, with more than 200 mm of rain every month and over 400 mm per month between December and March (the park is usually closed during this period). The best time for visiting this park is during the driest months (June-September), when average monthly rainfall drops below 100 mm. Annual average temperature varies from about 18°C in Cibodas to less than 10°C at the top of Gunung Pangrango while the relative humidity varies between 80% and 90%.

Annual rainfall is high. The average is in the range of 3,000-4,200 mm per annum, making the area one of the wettest parst of java. The rainy season occurs from October to May, the monthly average of 200 mm rising to over 400 mm in the period from December to March. The dry season occurs from June to September, rainfall dropping to below 100 mm per month. Visitors are asked to be especially careful at this time as the vegetation is easily ignited.

Relative humidity is likewise high, espesially in the forest at night. However, during the dry season humidity on the peaks swings from a night- time low of 30% to an afternoom high of over 90%. These variations have a marked effect on plant communities.

Daily temperature at Cibodas averages around 18°C, while on the peaks of Mount Gede and Pangrango the average is a chilly 10°C. Night-time temperature on the peaks may drop below 5°C. Frasts occur regularly so warm clothing is essential to anyone intending to climb to the summit. The National Park is an important hydrological catchment.