Port Moresby month by month, at a glance
Hover each month for the summary. Click to pin it.
New Guinea is one of the wettest islands on the planet: much of its territory passes 3,000 millimetres a year and some areas exceed 6,000. Port Moresby, its capital, receives 898.8 millimetres a year. It is the driest place on the whole island, and that anomaly explains the landscape, the calendar of a trip and even the trading history of this coast.
01 A rain shadow in the tropics
The cause is twofold. The south-east trade wind, which dominates half the year, blows parallel to this coast rather than into it, so it does not unload; and the city is ringed by high mountains that intercept the moisture before it arrives.
The result is a tropical savanna climate in the middle of a country of rainforest. The hills around Port Moresby are yellow grass and scattered trees, not closed forest, and in August you see columns of smoke from fires on the slopes.
Anyone arriving expecting the New Guinea of the documentaries gets a surprise. To find it you have to climb: half an hour's drive away and some five hundred metres higher, the tropical forest closes over again.
Key moments at a glance
12 mm over 4 rain days: sixteen times less than January.
14 mm and an average high of 29.9 degrees.
192 mm over 18 days, nearly a quarter of the year's total.
158 hours of sunshine, eighty-five fewer than November.
02 Six dry months and six wet
The split is about as clean as you will find. From December to March, 620 of the 899 annual millimetres fall; from June to October, across five months together, barely 77.
Rain days confirm it: eighteen in January and March, four in July and August. August is the driest month at twelve millimetres, and January the wettest at a hundred and ninety-two: sixteen times more.
April and May are the transition, at 105 and 56 millimetres, and November and December the way back, at 40 and 98. May already sits comfortably in the good stretch; November is workable and is also the sunniest month of the year, at 243 hours.
03 Steady heat, mild nights
Temperature moves little. Average highs run from 29.9 degrees in July to 32.5 in November, and average lows sit between 22.4 and 23.7 across all twelve months. The absolute heat record stands at 36.3 degrees.
The dry season is slightly cooler, and with lower humidity — 75 to 77 per cent against 81 or 82 in the wet months — how it feels changes rather more than the thermometer suggests.
One curious figure to place the climate: the absolute minimum on record is 10.4 degrees, in July. In a tropical city nine degrees from the equator that is almost an anecdote, but it explains why July nights are welcome.
04 Two thousand four hundred hours of sun
Port Moresby gathers 2,463 hours of sunshine a year, a high figure for the humid tropics. November leads with 243 hours, October follows with 231 and August adds 222; the minimum is February, at 158.
That abundance of light, along with the dryness, makes sun protection more urgent here than at other destinations in the region. It also makes dry-season afternoons spectacular from any hill in the city.
As for the sea, the coast is exposed to the trade wind through the dry half of the year, and that raises short chop and steady wind. For the water, the transition months tend to be kinder than the peak of the trades.
05 What to pack, and in short
Light breathable clothes, high sun protection and a hat, closed shoes for the grassy hills, repellent and a thin layer for July nights. In the wet season, add a rain shell and shoes that cope with mud.
In short: June to October without hesitation, July and August at the front; May and November work well; December to March it really rains and the sky closes over. In the driest city on the wettest island, the calendar is one of the easy parts.
