From Weather Underground's Weather Historian blog:
QUESTIONS CONCERNING THE WORLD’S HOTTEST TEMPERATURE ON RECORD: 136.4°F (58°C) AT AL AZIZA, LIBYA SEPTEMBER 13, 1922
One of the "sacred cows" of world weather extremes has been the widely reported "hottest temperature ever recorded on earth", a reading of 58°C (136.4°F) reported from Al Azizia (many different spellings), Libya on Sept. 13, 1922.*Back in 2008 we posted "What exactly is the worst climate in the world?":
This figure has been controversial since it first appeared in publications of climate data by Italian colonial authorities in their publication Il Clima di Azizia, Tripolitanai by F. Erndia and reprinted in the Quarterly Journal of the Royal Meteorological Society, 1924 (p.324,) and in the German climate science journal Meteorologische Zeitschrift 1925, p.39. This data originated from the publication R. Ufficio Centrale di Meteorologia e Geodinamica; Osservazioni dell anno 1922 Rome, Italy. For an image of the cover of this book please see http://www.wmo.int/pages/mediacentre/news_members/documents/Libya.pdf.
However, its validity was first raised in an article that appeared in the U.S. Weather Bureau's Monthly Weather Review article published (unedited) in May 1930 (p.209) written by someone using the initials A.J.H.:
"At once it appeared to me as striking that a temperature so high should occur relatively near the sea and in a region of only semi desert character. A comparison with the remaining Tripolitanian stations in the R. Ufficio Agrario, Sezione Meteorogica, Nr. 4, and 5, showed that the reading is about 20° higher than the maxima on the same day and on the preceding day at other stations: Tripoli, 115°; Sidi Mesri, 111°; Homs, 112°; and Zuara Marina, 117°. Also in the year 1923, when the publication gives 135° as the maximum for Azizia, all of the remaining stations, nine in number, have maximum temperatures 18° or more degrees lower..."
Al Azizia is situated at an elevation of 158 meters (520 feet approximately) about 55 kilometers (25 miles) south and a bit west of Tripoli. It was a major trading center for the Sahel Jeffara region, hence its military significance prior to WW II.
The Tripolitania region of Libya is subject to a foehn phenomena locally known as a Ghibli wind, akin to the Santa Ana winds of Southern California, but in this case related to offshore breezes originating in the Sahara Desert that, when conditions warrant, is similar to Santa Anas; hot air from the interior is forced over the coastal hills and is compressed and heated by downward sloping along the shore line and foothills along the leeward slopes, in this case the Jabal Nafusah mountains (highest peak being about 750 meters (2,500 feet) in northwestern Libya....MORE
From Mental Floss:
4 Places That Will Never See a Club Med
Whether a given climate is good or bad is subjective; to a native of northern Alaska, for instance, 75°F can seem miserably hot. But, in general, what makes for the worst climate depends on what you dread the most: fire or ice. Here are 4 places we’re not planning on setting up shop.
Anyone averse to fire should avoid spending a summer in Death Valley, California, where the average July temperature is 101°F, or Marble Bar, Australia, which once recorded 161 days in a row when the mercury topped 100°F. Even hotter—or at least more sticky—times can be had in Jacobabad, Pakistan.
Here the average June high temperature is 114°F, with relative humidity averaging nearly 60% in the morning hours.Dust storms are also frequent at this time of the year.
And the next three only get better.