🇵🇬Papua New Guinea

Papua New Guinea occupies the eastern half of New Guinea island plus the Bismarck Archipelago, Bougainville, and hundreds of smaller islands spanning roughly 462,840 km² between 0°–12°S and 141°–160°E. Dominated by the Owen Stanley Range and central Highlands rising to Mount Wilhelm (4,509 m, the highest peak), the terrain is extremely rugged with tropical rainforests covering much of the land, active volcanoes, and narrow coastal plains.

This topography generates a dramatic climate spectrum: equatorial tropical (Af) in the lowlands and coasts with year-round heat (26–32°C) and heavy rainfall, subtropical highland (Cfb) in the interior mountains with milder conditions in Mount Hagen and Goroka, and montane/alpine above 3,500 m on Mount Wilhelm with freezing nights. Papua New Guinea sits in the Western Pacific Warm Pool, the warmest ocean region on Earth, driving intense convection and making it one of the wettest countries globally.

Port Moresby (capital, rain-shadowed by mountains) sees highs of 30–32°C and nights around 23°C year-round with only about 900–1,200 mm rainfall (dry June–November, wet December–May). Lae has highs of 28–31°C and nights around 23°C with 4,600 mm distributed throughout the year. Mount Hagen (highland center, 1,677 m elevation) has a daily mean of about 18–20°C. Goroka (1,600 m) sees highs of about 26–27°C and nights around 15–16°C with roughly 1,700–1,850 mm. Rabaul (volcanic coast of New Britain) has highs around 31°C and nights around 24°C with about 2,000–2,200 mm.

Wewak has highs around 31°C and nights around 24°C with roughly 2,100 mm. Papua New Guinea experiences severe climate extremes amplified by ENSO and the Western Pacific monsoon: the severe 1997–98 El Niño drought-and-frost event killed crops across the Highlands, causing food shortages and hundreds of deaths; the 2015–16 El Niño triggered a drought emergency affecting an estimated 2.4 million people with crop failures and water shortages; the May 2024 Enga Province landslide buried an estimated 670 to over 2,000 people (heavy rain is a suspected cause); tropical cyclones such as Cyclone Guba (2007, 149 deaths, severe Oro Province flooding); sea-level rise is displacing Carteret Islanders (often called the first climate refugees, relocating since 2009) and threatening other low-lying atolls; and the February 2018 Highlands earthquake (M7.5) caused 160 deaths and massive landslides.

Comparing the last decade against the 1940–1970 baseline, mean temperatures across these cities have risen by about 1.4°C.