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Questions Concerning the World Record 136.4°F (58°C) at Al Aziza, Libya

By: Christopher C. Burt, 1:50 PM GMT on October 08, 2010


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, Libya on Sept. 13, 1922. There are many different spellings of this location:

al 'Aziziyah
El Azizia
El Azizya
Al Azizi

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.

Extreme maximum temperatures are the result. There is little doubt that the Ghibli wind phenomena was occurring on this date in Libya given the extreme temperatures reported from Tripoli (25 miles north by northeast of Al Azizia) and other locations in the coastal plain along the Mediterranean there. August and September are the months that these events are most common here, just as September and October are the months Santa Anas are most likely to form along the coast of Southern California. Note in the map above that the most of the known temperatures recorded on Sept. 13, 1922 were from coastal locations. However, during offshore foehn events interior locations are not necessarily hotter than coastal ones. Sidi Mesri, for instance (about 7 miles inland), was actually cooler than the Tripoli reading. It is highly unlikely that a reading some 20°F warmer could have occurred a further 18 miles inland from Sidri Mesri.

In this analysis I am only concerned about the extreme reading at Al Azizia.

In the 1950s Italian physical scientist A. Fantoli examined the thermometer and the shelter used in this world-record temperature observation. His conclusions were reported in two publications:

A. FANTOLI, I valori medi della temperatura in Libia, «Bollettino della Società Geografica Italiana», vol. 7, nn. 1-2 (1954), pp. 59-71.

A. FANTOLI, La più alta temperatura del mondo, «Rivista di Meteorologia Aeronautica», vol. 18, n. 3 (1958), pp. 53-63.

The crucial part of his reports concerned the exposure of the thermometer at the site and the thermometer itself :

1-Che se nel 1922 non si poté far altro che accogliere la cifra su esposta, del resto esplicitamente confermata, via radio, dall'autorità militare locale (el-Azizìa rimase per vario tempo isolata per ragioni contingenti) e quindi dalla scheda delle osservazioni, quando fu possibile raggiungere quel centro, si poté constatare che gli estremi termici erano stati ricavati mediante un termometro Six-Bellani essendosi guastato quello a massima della coppia ordinaria di dotazione»

2-La capannina con persiane semplici (abri, tipo inglese) veniva quindi a trovarsi a 5,5 metri dal suolo, a 48 circa sul piano medio della pianura circostante ed a 163 metri sul livello del mare. La base della capannina (isolata da tutte le parti) era stata fissata con staffe sul piano della terrazza, rivestito d'una copertura di cemento incatramato. Gli strumenti erano collocati nel modo usuale: anemoscopio e pluviometro situati a conveniente distanza; l'anemometro a mano (anemometro tipo Salmoiraghi) veniva portato in terrazza ad ogni osservazione.

This is translated as such (the language in his original report was of an archaic type and difficult to translate into English verbatim--italics indicate my own notes):

1- "So in 1922 you could not help but accept the figure on display, also explicitly confirmed by radio, by the local military (el-Aziz was isolated for some time for strategic reasons) and then by the observation log sheet when it was possible to see that data, you could see that the extreme heat was measured by a thermometer Six/Bellani having failed the other thermometer's "maximum potential" of the ordinary equipment (referring to, apparently, another thermometer on site that was not self-registering or capable of recording a value as high as 58°C). NOTE: The "Six/ Bellani" refers to this type of thermometer:


...and was used to record the 58°C since it was capable of being self-registering--.i.e. max and min temperatures recordings without human observation--unlike the "ordinary" thermometer apparently also in use at the site. The use of a self-registering instrument, such as this, throws more doubt on the observation implying that no human observation was made at the site that day).

2-The simple shelter with simple shutters (Abri, English type) (the term of an "abri English "type shelter" is not understood although "abri" is a French word for "shelter" perhaps he is just saying it was a standard shelter commonly used in Europe at that time) was fixed at 5.5 meters (sic) it must have been 5.5 feet not meters otherwise a 20 foot ladder must have been used to reach the shelter!) above the ground, at (an elevation) 48 meters above the surrounding plain, and at 163 meters above sea level. The base of the shelter (enclosed on all sides) (we will give the benefit of doubt here that the shelter was louvered as per a Stevenson screen) had been fixed by brackets on the floor of the terrace plaza, which was coated with a covering of tarred concrete. The instruments were placed in the usual way: anemometer and rain gauge located at a convenient distance away, the hand airspeed indicator (anemometer type Salmoiraghi) was taken on the terrace at every observation."

The key sentence being that the shelter "...was fixed on the surface of the terrace plaza which was covered by tarred concrete." The color of the concrete is not noted, but to the best of my knowledge most tarred concrete is black.

The WMO extreme weather records committee has this discussion concerning the measurement:

WMO Extreme Weather Records Committee Discussion
"An Italian weather station measured a temperature of 136.4°F (58°C) in al' Aziziyah (Azizia) Libya (about 25 miles south of Tripoli). Although this record has gained general acceptance as the world's highest temperature recorded under standard conditions, the validity of the extreme has been questioned. Fántoli (1954,1958) examined the record and researched the exposure, the instrument shelter, and the instruments themselves. A discussion in English of Fántoli's 1954 work appears in Gentilli, 1955. Fántoli generally concluded that the probable extreme maximum should have been only 132.8°F (56°C). Lamb (1958) noted that the extreme occurred following two days of hot, southerly winds and that latent heat may have been added to the air mass due to rain south of location."

Temperature records at this site were first established in 1919 by the Italian military at a farm 25 miles south of Tripoli. This farm may, in fact was almost certainly, being used as a military station. In 1926 the instruments were replaced and the location moved to a site nearby and put in civilian hands. Some references claim members of The National Geographic Society provided the instruments in 1913 (see "Change in the Weather" by Philip Eden p.195, The Daily Telegraph publishers, London, UK, 2005). Correspondence with NGS has indicated that this was not the case. They have no record of anyone from their organization providing such equipment at this time or at anytime in Libya. Here is correspondence received from them on March 8, 2010:

"Thank you for contacting the National Geographic Society.

The Society does not have meteorological stations. We reported on the highest temperature ever recorded at El Azizia; however, the recording equipment was not ours.

The World Meteorological Organization website indicates there is no information available on the actual equipment used to record the temperature:

http://www.wmo.int/pages/mediacentre/news_members /documents/Libya.pdf

I hope this information is helpful.

Sincerely yours,

Julie Crain
National Geographic Society."

After the location was moved, sometime in 1926, regular temperature data was supplied until 1942 when WWII interrupted such and the Italian authority was displaced.

The station was reestablished in 1947 following the war at the same site and continued in operation until 1984. In 2007 a new site was under construction for the weather station and the progress on this is undetermined.

Here is a chart of the extreme maximum monthly temperatures recorded at Al Azizia from 1920-1942 (centigrade):

Note the many extreme readings of 52°C+ (125.6°F) prior to 1927 and especially the 130°F+ readings in Aug. 1923, and Sept. 1923. No reading above 45.9°C (114.6°F) was recorded in September following the change in site and instrumentation. In fact the hottest post-1927 reading was 51.9°C (125.4°) in June 1928. Nine 50°C (122°F) readings were recorded between 1920 and 1926, with just 2 such from 1927 through 1942. The average absolute maximum temperature for September was 48.3°C (118.9°F) for the period of 1920-1926 and 42.4°C (108.3°F) for the period of 1927-1942. For August this average was 51.2°C (124.2°F) for 1920-1926 and 44.6°C (112.3°F) for 1927-1942. So the average absolute maximum temperatures for the period of 1920-1926 in August and September were some 10°F higher than for those same months in the 1927-1942 period of record.

(* Thanks to Khalid Ibrahim El Fadli, Libyan National Meteorological Center (LNMC) in Tripoli for this data.)

If one looks at the September average monthly temperature record for 1919-1940 one can see an anomaly in the pre-1927 record:

IMPORTANT UPDATE: This plot does not represent "average monthly temperature record" but mean daily temperature amplitude (difference between daily min and max) in September 1919-1940, and it's in degree Celsius.

Much higher values at 20s strongly suggests that there was exposure problem (minimum temperatures remained at normal levels, but maximum temperatures was increased which affected daily amplitudes)

Best Regards
Piotr Djakow (Mr. Djakow produced this graphic in an analysis of the Azizia record he recently posted in Polish). For a translation of this see the comments section and comment #23 by Neaplolitan.

The temperature observations at Al Azizia prior to 1927 (when the site and instruments were changed) are obviously invalid. The ONLY consideration to accept the 58°C figure is that this was a result of a heat burst from dissipating rain showers in the hills south of the site (as per the WMO conclusion noted before). However, this does not explain the other inconsistent readings in other months and years from the station prior to 1927. So this potential argument in favor of the reading on Sept. 13, 1922 is also invalid. Mr. Fantoli's recommendation of a lower more reliable reading of 132.8°F also does not stand up accordingly. The shelter housing the thermometer was most likely over exposed and measuring heat radiating of off the black-tarred concrete of the terrace on which it was placed. It is likely that the absolute maximum temperature conceivable at the site on this date was no more than 120°F at best. The highest authenticated temperature measured in Libya's modern records is a reading of 50.2°C (122.4°F) at Zuara in June of 1995.

So if Al Azizia, Libya's 58°C (136.4°F) is not the hottest reliably measured temperature in the world, what is?

Stay tuned to my blog the week of Oct. 18-25 for this.

A. FANTOLI, I valori medi della temperatura in Libia, «Bollettino della Società Geografica Italiana», vol. 7, nn. 1-2 (1954), pp. 59-71.

A. FANTOLI, La più alta temperatura del mondo, «Rivista di Meteorologia Aeronautica», vol. 18, n. 3 (1958), pp. 53-63.

USWB, Monthly Weather Review, May 1930 p.209.

Eden, Philip, "Change in the Weather", Continuum Publishers, London, 2005 p.194-195.

"Weather and Climate Extremes" by Dr. Paul F. Krause and Kathleen L. Flood, US Army Corps of Engineers, Topographic Engineering Center, Report TEC-0099, 1997.

Al-Fenadi, Younis, Hottest Temperature Record in the World, El Azizia, Libya, Libyan National Meteorological Centre.

World Meteorological Organization (WMO) and Arizona State University World Weather Extremes Committee.

Thanks to Maximiliano Herrera, Piotr Djaków , Howard Rainford, Khalid Ibrahim El Fadli (Libyan National Meteorological Center), and Federico Noris (for translation of Fantoli notes) for their contributions to this article.

Christopher C. Burt


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.