The year in the Northern Territory, month by month
The figures come from two stations, 1991–2020 series: Darwin (1,832.4 millimetres a year over 96.5 days) and Alice Springs, some 1,500 kilometres to the south (274.8 millimetres over 28.6 days). The scoring crosses rain, humidity, heat and how usable the roads are.
There are destinations where choosing the month is a matter of fine tuning. In the north of the Northern Territory it is not: the difference between the two halves of the year is the difference between being able to get around and not.
01 A binary calendar
Darwin's figures are among the most asymmetric you will find in a climate series. In January 470.7 millimetres fall over 19.6 days; in August, 0.8 millimetres over 0.2 days. The ratio between the two months is nearly six hundred to one.
Grouped by quarters it is clearer still. December, January and February add up to 1,162.4 millimetres, more than a metre of water. June, July and August add up to 3.8 millimetres over 0.5 rainy days between the three of them.
That is why nobody here talks about winter and summer. They talk about the wet and the dry, and they are two different regimes with two different landscapes, not two degrees of the same thing.
A metre of water in three months and four millimetres in the next three: the year does not shade, it splits.
02 The thermometer, which says nothing
What makes this calendar singular is what does not change. Darwin's average high runs from 31.1 degrees in June and July to 33.8 in October: 2.7 degrees of range across the whole year. The average low moves a little more, from 19.3 to 25.5.
In other words: a temperature forecast is no use for telling which month you are in. If someone tells you it is thirty-two degrees in Darwin, you have learned nothing about the date.
What does distinguish the seasons, besides the rain, is humidity. In the dry, afternoon humidity falls to 36 per cent and in the wet it rises to 74. At the same temperature, those thirty-two degrees feel completely different.
And sunshine goes with it. February has 162.4 hours of sunshine and August 325.5: exactly double. The wet season is not only wet, it is dark.
03 The worst month is not the wettest
Between the two seasons there is a stretch that residents name in their own right and that is worth knowing before you book: September, October and November.
In that stretch humidity rises from 47 to 58 per cent, highs reach October's 33.8 degrees, the highest of the year, and the rain has not yet properly arrived: 14.3 millimetres in September and 68.9 in October.
It is the worst combination: maximum heat, high humidity and no storm to release it. The wettest months are uncomfortable for other reasons, but at least it rains.
04 And in the centre, exactly the opposite
Some 1,500 kilometres to the south, in the centre of the territory, the pattern inverts point by point. Alice Springs receives 274.8 millimetres a year over 28.6 days, with no wet season to speak of: rain is spread out and there is little of it in any month.
What does vary there is temperature, and brutally. The average high runs from 37.1 degrees in January to 20.1 in June: 17 degrees of range, six times Darwin's. And July's average low is 3.9 degrees, with an absolute record of −7.5.
Hence a warning that surprises many people: in central Australia you get cold. Anyone camping near Uluru in July needs a proper sleeping bag, and Alice Springs' heat record, 47.5 degrees, is from December.
05 What the season closes and what it opens
The harshest practical consequence concerns access. In the wet season, much of the unsealed track network in the north is closed, watercourses overflow and there are areas of national parks that simply do not open for months.
The counterpart is that the wet season is when the landscape works. The waterfalls carry water, the floodplains fill and the north is green, which is exactly what nobody sees if they travel only in the dry.
And there is an in-between moment that pays off: the end of the wet and the start of the dry, between April and May. Water is still on the plains, the tracks have reopened and wildlife concentrates in the remaining waterholes.
06 How to choose the month
If you are going north, May to August, no argument. Those are the four months of 0.8 to 20.7 millimetres, with humidity between 36 and 41 per cent and up to 325.5 hours of sunshine. Everything else in the year is an exception that needs justifying.
If you are going to the centre, the window is similar but for another reason: from May to August Alice Springs' highs run from 20.1 to 23.6 degrees instead of January's 37.1. The price is the nights, which drop to 3.9.
And if you want the north with water, April. It is the month when rain collapses from 313.7 to 105.1 millimetres and rainy days from 16.8 to 7.6, with the plains still flooded. It is the only point in the calendar where you see both things at once.
The year's four stretches
From 279.3 to 470.7 millimetres a month in Darwin, over 15.0 to 19.6 days, with afternoon humidity between 66 and 74 per cent and sunshine at its annual minimum. Many northern tracks are closed.
Rain goes from 313.7 to 105.1 millimetres and rainy days from 16.8 to 7.6 in a single month. Water remains on the floodplains but the sky opens: 264.0 hours of sunshine against March's 213.9.
From 0.8 to 20.7 millimetres a month in Darwin, over 0.1 to 1.7 days. Highs of 31.1 to 32.3 degrees, humidity of 36 to 41 per cent and up to 325.5 hours of sunshine. This is the season, no argument.
Darwin's highs climb to 33.8 degrees, humidity from 47 to 58 per cent and rain from 14.3 to 143.5 millimetres. The most uncomfortable stretch of the year: already muggy and not yet properly raining.
