Summertime Arab Coups of the 50s, 60s and 70s: Was it the Weather?

I'm working on a post for tomorrow which will note the 52nd anniversary of the overthrow of the monarchy in Iraq (the July 14 revolution), and last July 23 I reflected on Egypt's comparable moment; which raises another issue: why have so many Middle Eastern coups occurred in the summertime? Is it the heat, or what? Admittedly, coups are mostly a thing of the past in the Arab world today. Syria, which had something like 20-plus coups and attempts between 1949 and 1970, has settled down to being run by Asads for the past 40 years. Other than Mauritania, which keeps the tradition alive, the last successful Arab coup was Sudan's in 1989, 21 years ago. But in the golden age of coups, a lot were in summertime.

This is not as frivolous as it sounds. Last year the North African blogger who calls himself The Moor Next Door took the time and trouble to actually do spreadsheets and graphs of all Arab coups and attempted coups, and sure enough, he found a lot in the summertime: in fact, he found seven in July and five in August. These were by far the most except for the outlier November, which also had seven. (See his post here; a spreadsheet of coups here; and graphs of the data here.)

It does make you wonder. The Free Officers' coups in Egypt and Iraq are not alone: the Ba‘athist coup of July 17, 1968 was the key to the long rule of Saddam Hussein; in Syria, Husni Za‘im was overthrown in August 1949; in July 1963 a Nasserite counter-coup was put down bloodily; in Iraq Bakr Sidqi, who launched the first modern Arab coup in 1936, was assassinated in August 1937; a July 1971 coup in Sudan succeeded until Egyptian troops intervened to restore Ja‘far Numeiri; Sultan Qaboos of Oman deposed his father in July 1970; and so on. Mauritania, the only Arab country that still has coups these days, has had them (among others in other months) in July 1978, August 2005, and August 2008.

So is it the heat, or is all this coincidence?