The climate in Papua New Guinea is hot and humid throughout the year along the coasts and in the plains, while it is progressively cooler, and then colder, as you go up in altitude. In much of the country, covered with dense rainforests, there is no dry season, so we can speak of equatorial climate, while in some inland valleys and along the south coast, there is a relatively dry season from July to September, and therefore the climate is tropical.
The climate is influenced by the monsoon circulation: the northwest monsoon prevails from December to April, and the southeast monsoon from May to October. Usually, each monsoon brings rainfall on the exposed slope, but in many areas, it rains during both the monsoons, so it rains all year round.
Rainfall typically ranges from 2,000 to 4,000 millimeters (80 to 160 inches) per year, with some higher peaks on the most exposed slopes, where it reaches as high as 7/8 meters (23/26 feet) per year, while it drops to 1,000/1,500 mm (40/60 in) on the southern coast, overlooking the Gulf of Papua and the Coral Sea.
On the coasts, the temperatures are high and stable throughout the year in the north, around 30 °C (86 °F) during the day, while in the south, located farther from the Equator, they decrease a bit in the period that can be called winter, from June to September.
Papua New Guinea is an island state, formed by the eastern part of New Guinea (the western part belonging to Indonesia) plus some smaller islands (including New Britain, New Ireland, Manus and Bougainville).

Papua New Guinea

Equatorial climate


In Madang, on the north-eastern coast of New Guinea, 3,500 mm (138 in) of rain fall per year, with a maximum of 430 mm (17 in) in April and a minimum of 120 mm (4.7 in) in August, so we are in the area that has an equatorial climate. Here is the average precipitation.
Madang - Average precipitation

As mentioned, temperatures along the coasts are high throughout the year, and in particular, they are very stable in the areas with an equatorial climate. Here are the average temperatures of Madang.
Madang - Average temperatures
Min (°C)232323232322222222222323
Max (°C)303030303030292930303030
Min (°F)737373737372727272727373
Max (°F)868686868686848486868686

The amount of sunshine on the coasts is generally decent, but not exceptional; however, it is a little higher from May to October. Here are the sunshine hours in Madang.
Madang - Sunshine

To the east of the eastern part of New Guinea, which constitutes the largest portion of the country, the islands (including New Ireland, New Britain and Bougainville) are very rainy throughout the year as well. In general, the rains are most abundant from December to April, but not everywhere: in Lae, facing south-east in the Huon Gulf, the rains are most abundant in July and August, when more than 500 mm (20 in) fall per month.

Tropical climate

Port Moresby

The capital, Port Moresby, is located in the southern area, which, as mentioned, is less rainy and more sheltered, so much so that it receives only 1,000 mm (40 in) of rain per year, with a relatively dry period from May to November, when rainfall drops below 70 mm (2.8 in) per month; in particular, the rains are scarce from June to October. Here is the average precipitation.
Port Moresby - Average precipitation

In the capital, the best period is the one that runs from June to September, in fact, it is also the least hot, with maximum temperatures around 29/30 °C (84/86 °F), instead of the 31/32 °C (88/90 °F) that are recorded in the rest of the year. Here are the average temperatures.
Port Moresby - Average temperatures
Min (°C)232222222222212122222223
Max (°C)313131313030293030313232
Min (°F)737272727272707072727273
Max (°F)888888888686848686889090

Being that the rains are less frequent, the amount of sunshine in Port Moresby is higher than in other areas of the country.
Port Moresby - Sunshine

The sea is always warm enough for swimming throughout the country, although in the southernmost part, where the capital is located, it becomes a bit less warm from July to October, as we can see in the following table.
Port Moresby - Sea temperature
Temp (°C)292929292827262526262829
Temp (°F)848484848281797779798284


The interior of the mainland (eastern New Guinea) is crossed by mountains: in the north, we find the Victor Emanuel Range and the Bismarck Mountains, the latter culminating in Mount Wilhelm, 4,509 meters (14,793 feet) high, while in the south, we find the Owen Stanley Mountains, whose highest peak is Mount Victoria, 4,038 meters (13,248 feet) high.
At 1,500 meters (5,000 feet) of altitude, the temperature is pleasant: cool at night and warm during the day.


Here are the average temperatures of Goroka, located at 1,600 meters (5,2520 feet) above sea level, in the Eastern Highlands province.
Goroka - Average temperatures
Min (°C)161616161515151516151616
Max (°C)272626272626262626272728
Min (°F)616161615959595961596161
Max (°F)817979817979797979818182

In Goroka, 1,700 mm (68 in) of rain fall per year; there is a relatively dry season from June to August, when, however, some showers can still occur.
Goroka - Average precipitation

The sun in the mountainous areas shines less often than on the coasts, and the sky is often cloudy.
Goroka - Sunshine

Above 3,500 meters (11,500 ft), the forest is replaced by a sparse mountain vegetation: here, the cold is constant and sometimes it can even snow.
From the mountains, numerous rivers flow, such as the Sepik and the Fly, which in lowland areas, often at great distance from the mouth, give rise to marshes and swamps, where mangroves and gallery forests grow.

Tropical cyclones

Papua New Guinea can be affected by tropical cyclones of the South Pacific. Typically, cyclones are formed from November to mid-May, although they are more likely from late November to mid-April. The part of the country that is directly affected is the center-south. The map below is an indication of the areas that have been affected in the past. The northern areas, however, may be partly affected, with an increase in wind, clouds, and waves.

Papua New Guinea, zone affected by cyclones

The climate of Papua New Guinea is also influenced by the so-called ENSO cycle. In El Niño years, the rainy season is warmer and drier than normal, and the monsoon arrives often late, while the dry season is cooler than normal in the south. On the other hand, in La Niña years, the rainy season from December to April is more intense than normal and can lead to flooding, while the dry season is warmer than normal in the south. During neutral phases (neither El Niño nor La Niña), however, it's more likely for cyclones to form.

Best Time

The best time to visit the southern coast of Papua New Guinea, which includes Port Moresby, runs from June to August or September, since it is the driest and the least hot period of the year. Along this coast, in the months of May, October, and November, the rains are rare as well, but they are a bit hotter.
On the contrary, as previously mentioned, the other parts of the country do not experience a real dry season, in fact, they are rainy all year round, and some areas, such as the coast where Lae is located, receive the greatest amount of rainfall right in this period. However, the best period to visit the country as a whole is still from June to August, remembering that there can be showers and thunderstorms, more or less intense, in many areas.

What to pack

All year round, bring tropics-friendly, loose-fitting clothing, a sun hat, a scarf for the breeze, a light sweatshirt for the evening, and a light raincoat or umbrella. When going to the reef, you can bring snorkeling equipment, including water shoes or rubber-soled shoes.
In inland areas, around 2,000 meters (6,500 feet), bring spring/autumn clothes, a sweater and a jacket for the evening, and an umbrella. For the highest peaks, warm clothes, such as a down jacket, gloves, a hat, and hiking boots.