Papua New Guinea has a monsoonal climate characterized by high temperatures and humidity throughout the year. Two monsoonal seasons are recognized: the northwest monsoons, which occur from December to March, and the southwest Monsoons, which occur from May to October. Indeed, the country is home to one of the wettest climates of the world and rainfall in many areas of the country exceeds 2500 mm, with the heaviest events occurring in the highlands. Temperatures are relatively steady across the country, and mean temperatures in Port Moresby range from 26°C to 28°C. Climate in this part of the Pacific is governed by a number of factors, including the trade winds and the movement of the South Pacific Convergence Zone (SPCZ), a zone of high pressure rainfall zone that migrates across the Pacific south of the equator. Year to year variability in climate is also strongly influenced by the El Niño conditions in the southeast Pacific, which bring drought conditions to PNG, especially in the drier areas of the country. Areas with a pronounced wet and dry season that receive less than 2000 mm rainfall include: Markham Valley, Bulolo Valley, Maprik—Angoram area, Eastern highlands, and coastal areas near Cape Vogel, Port Moresby, and Daru. Key historical climate trends are summarized below:
- For Papua New Guinea, the overall observed near surface temperature trend (0.50ºC) resembles both the global and tropical Asian trend, with an overall error of +/- 0 .15ºC.
- Mean temperatures across the South Pacific have increased by 1°C since 1970 (0.3°C per decade).
- The numbers of hot days and hot nights have increased significantly across the Pacific.
This section provides the options to visualize historical climate data for different timeframes via map and annual cycle chart.