The city receives 116 millimetres of precipitation a year, all of it between October and April, and its annual mean temperature is 27.2 degrees. With those two figures the calendar sorts itself out: there is half a year when the city can be walked and half a year when it simply cannot.
01 Zero, four months running
The drought figures, in a row: May 0.4 millimetres, June 0.0, July 0.0, August 0.0, September 0.0 and October 1.4. That is, there are five consecutive months averaging practically nothing and four averaging exactly zero. All the year's rain falls between November and April, with January leading at 30.2 millimetres.
02 Forty-six degrees on average
It is worth reading the summer average highs twice, because they are not records: they are the norm. June 45.1 degrees, July 46.6, August 46.4 and September 43.0. The absolute record of the series, measured in the city, is 52.1 degrees in July, and that series starts in 1956.
But the figure that really decides is the minimum. In July the average low is 30.4 degrees and in August 29.7: it does not drop below thirty even before dawn. That means there is no hour of the day when you can comfortably be outside, and that the famous trick of starting early does not work here.
In July the average low is 30.4 degrees. There is no cool hour: it does not exist.
03 Winter genuinely exists
The calendar's surprise is at the other end. January has an average high of 19.6 degrees and a low of 7.6, and the series' cold record is −4.0 degrees, with sub-zero values also recorded in February and December. In a city we associate with extreme heat, that throws you, and it is worth packing something warm.
Winter is also the only wet season, and here rain has a practical consequence it would not have elsewhere: on ground with no natural drainage and in a city built on the assumption that it does not rain, a 20-millimetre downpour can flood streets and snarl traffic for hours. These episodes are short and infrequent, but they should be reckoned with.
04 Dust and haze
There is a third variable that does not appear in the table and is worth keeping in mind: dust. On a desert plain with no vegetation, wind lifts particles easily, and there are days — especially in spring and summer — when visibility drops sharply and the sky turns white or brown.
For the traveller that has two effects. The first is photographic: on a hazy day the horizon disappears and long views are lost. The second is respiratory, and if you have asthma or allergies it is worth checking the forecast and carrying a mask on bad days, exactly as you would check rain elsewhere.
05 The verdict
February, by a clear margin. It combines a high of 22.1 degrees and a low of 9.1 — walk-all-day and eat-outdoors temperature — with only 10.5 millimetres of rain, and it falls in the least dusty stretch of the year. March is the second option and rises to 26.5, still perfectly comfortable.
And the warning that sums up the article: from May to September this destination is not a matter of discomfort but of impossibility. At a high of 46.6 degrees, lows above 30 and no rain at all, no scheduling strategy fixes it. If your dates fall there, change the destination or change the dates.
