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It was widely reported that on 28th June, 2019, a record temperature of 45.9°C was recorded in Gallargues-le-Montueux, France, breaking the previous 2003 record of 44.1°C. Sources: Metéo France, BBC, CNN.

It was then alleged that this was, in fact, not the highest-ever temperature recorded in France, and that in August 1930, a temperature of 122 Fahrenheit (50°C) was logged in the Loire region. E.g. Watts Up With That, @drwaheeduddin.

The reasoning behind these challenges was several Australian and New Zealand papers reporting this temperature on 29th and 30th August 1930. For example, the Sydney Evening News (Trove Source):

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The Queensland Telegraph, The Western Argus and the (NZ) Horowhenua Chronicle and others reported identical figures: Trove Search Results.

Furthermore, many of these claimed this was the highest since 1870, implying yet-greater historical highs.

Was a temperature of 122F really recorded in 1930 in France, and if so, are the measurements directly comparable?

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    Re *Furthermore, many of these claimed this was the highest since 1870, implying yet-greater historical highs.* The 1870s mark the time when modern weather keeping standards were first set. All records prior to that are somewhat suspect. A thermometer exposed to sunlight, a thermometer on hot pavement, a thermometer hundreds of meters above the surface, and a thermometer intentionally shaded and a bit above the surface of the Earth (1.25 meters to 2 meters) will record markedly different temperatures. There were no standards prior to 1873, when the World Meteorological Organization was formed. – David Hammen Jul 03 '19 at 01:18
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    Looking at a [ten-minute record for Gallargues-le-Montueux on 28 Juin 2019](https://www.infoclimat.fr/observations-meteo/archives/28/juin/2019/gallargues-le-montueux/000OZ.html?dixminutes) the highest figure seems to be 44.2°C at 16:40 rather than 45.9°C – Henry Jul 03 '19 at 07:46
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    Discussing whether the Gallargues-le-Montueux measurement is invalid is pointless if the question is whether the previous temperature record of 44.1°C was broken on June 28. The Météo-France article shows 12 other stations that surpassed that mark on that day. The second on the list (Villevieille, a town very close to Gallargues-le-Montueux) is listed with 45.4°C, and Marsillargues in the same area is listed with 45.1°C. Of course, following the WUWT way of argumentation, we can't know for sure if there weren't ice-cream trucks parked at all these stations falsifying these measurements. – Schmuddi Jul 03 '19 at 09:41
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    "France" is also not what you might think it is. I am sure "France" has had many days logged in the 50s˚C. There are two parts to "France", the Republic Francaise and the "Dom Tom". See https://en.wikipedia.org/wiki/File:France_in_the_World_(%2BAntarctica_claims).svg – Douglas Held Jul 03 '19 at 20:53
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    I'm pretty sure they registered even higher temperatures even earlier, in a bakery or a foundry. (this is why it's important to check where it was measured and how) – vsz Jul 04 '19 at 06:04
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    @DouglasHeld you're wrong, DOMs are part of the French Republic (note that "Francaise" isn't a word in either French or English), not separate from it. Also they're mostly islands, which means they have a very stable climate, and so recordings above 50°C would be extremely surprising, even though the average temperature is higher than in mainland. – Grimmy Jul 04 '19 at 10:21
  • Yes, warm air masses from down south seem to invade Europe quite often now. Living a bit northerly of France, 2017 was an extremely dry and hot summer. The first time I felt a "hot air dryer" wind coming in from the countryside and I have seen some summers since '70s, it was amazing. Corn was dying in the field until you got something that looked as it came out of Ethiopian Disaster report. This summer is not bad either, let's see how it develops. The weather patterns, they be a-shifting, no doubt about that. – David Tonhofer Jul 04 '19 at 11:15
  • @vsz or even in my oven (which is in France), it frequently goes around 200°C – Rafalon Jul 05 '19 at 12:42
  • Related: https://skeptics.stackexchange.com/questions/43386/were-50c-122f-days-recorded-across-australia-during-the-1800s – Michael W. Jul 05 '19 at 23:42
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    @Grimy but Algeria was party of France for over a century, and 50 degrees seems quite plausible there. I think the more useful discussion would be limited to historical records for current French territory, however. – phoog Jul 06 '19 at 00:44
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    @Grimy oh, I guess I meant France métropolitaine – Douglas Held Jul 07 '19 at 16:23

1 Answers1

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The 1930 measurement was taken incorrectly.

The claim was also made in domestic newspapers at the time, including L'Express du Midi:

50° AU SOLEIL A SAINT-ETIENNE

Saint-Etienne, 27 août. Le thermomètre a marqué aujourd'hui 50° au soleil. Mme Guilly, 40 ans, est morte frappée d'insolation.

A rough translation of this is

50° IN THE SUN IN SAINT-ETIENNE

Saint-Etienne, August 27th. The thermometer today measured 50° in the sun. Mrs. Guilly, 40, died of sunstroke.

Note the key phrase "in the sun". (The paper you mention explicitly states that the Paris temperature recording was made in the shade, as opposed to direct sunlight.) None of the newspapers give additional information about the measurement (e.g. how long the thermometer was exposed for, was it near other heat sources, etc.). Without knowing whether the reading was contaminated, it seems unfair to claim that the measurement then should get the record. Indeed, if the measurement was taken in the Sun, that should make the measured temperature hotter than the actual air temperature, contaminating the dataset. It's recommended to place a thermometer in the shade for accurate temperature measurements - and the Saint-Etienne reading did not, apparently, come from that.

In particular, an official temperature measurement should use a thermometer in a Stevenson screen (thanks, David Hammen). The ideal height is 1.25 to 2 meters off the ground, and the instrument should obviously be placed in an area that has the same average temperature as the region it's trying to represent. L'Express du Midi implies that a Stevenson screen was not used at Saint-Etienne, and it's quite possible that other modern recommendations were not obeyed. Notably - and ironically - the Watts Up With That article does show a thermometer in a Stevenson screen, as it should be. Official temperature measurements use Stevenson screens.

It's also worth noting that none of the temperature record I've found for Saint-Etienne from 1930 shows this data point; indeed, it seems that the temperature didn't deviate from the average significantly. While June seems to have been one of the hottest months on average that year, there's no enormous outlier shown - possibly because the measurement was likely performed incorrectly.

Additional sources: Fake Investigation, ClimateState.com

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HDE 226868
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    Official temperature readings need to be taken from a thermometer that is 1.25 meters to 2 meters above the surface and is shaded from sunlight by a structure such as a [Stevenson screen](https://en.wikipedia.org/wiki/Stevenson_screen). – David Hammen Jul 03 '19 at 01:09
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    @DavidHammen: Do you have a reference for that? – Oddthinking Jul 03 '19 at 01:21
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    @Oddthinking - [Official weather measurements are made at using standard equipment at a fixed height of between 1.25 m (4 ft 1 in) and 2 m (6 ft 7 in) above the ground for a fixed location over a specific length-of-record.](https://web.archive.org/web/20131213113854/http://wmo.asu.edu/) – David Hammen Jul 03 '19 at 01:24
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    @Oddthinking I've found at least one; the Australian government's page (which I've linked to) recommends a minimum height of 1.2 meters above the ground. (I'm not sure how important a detail it is, though; we have no idea if the Saint-Etienne station complied with *any* modern procedures, let alone the correct height above ground of the thermometer.) – HDE 226868 Jul 03 '19 at 01:24
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    @Oddthinking - Even better, the World Meteorological Organization [Guide to Meteorological Instruments and Methods of Observation](https://library.wmo.int/doc_num.php?explnum_id=4147) specifies that (continued) – David Hammen Jul 03 '19 at 01:46
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    "In order to achieve representative results when comparing thermometer readings at different places and at different times, a standardized exposure of the screen and, hence, of the thermometer itself is also indispensable. For general meteorological work, the observed air temperature should be representative of the free air conditions surrounding the station over as large an area as possible, at a height of between 1.25 and 2 m above ground level." – David Hammen Jul 03 '19 at 01:46
  • the 45.9 was also incorrect, it was directly in harsh sunlight over a dark reflective glazed tile roof... – jwenting Jul 03 '19 at 07:57
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    @jwenting If you have a reliable source for that, do post it as an answer, because in that case the answer to the claim is "incorrect". But this measurement is [reported by Meteo France](http://www.meteofrance.fr/actualites/73726667-record-absolu-45-9-c-c-est-la-temperature-la-plus-chaude-jamais-mesuree-en-france), so it seems unlikely that what you claim is accurate (and if it *was* measured directly in harsh sunlight, it would have reported much, much more than 45.9°C) – gerrit Jul 03 '19 at 08:12
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    @gerrit Jwenting is mistaken. There's a report on Facebook from a NonProfit (https://www.facebook.com/infoclimat/posts/2311418428925836, in French but translation is mostly readable) which explains it. Essentially, there are 2 weather stations in the record setting town: one from the official French weather bureau setup according to the regulations, and one from a local amateur meteorologist club which isn't setup according to regulations. The station jwenting talks about is the amateur one, but the record measurement was taken by the official Meteo France one. – Nzall Jul 03 '19 at 11:40
  • @Nzall it would be great if you could make that the topic of another question. – leftaroundabout Jul 03 '19 at 13:46
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    I'd suggest "read" or "measured" instead of "marked" in the translation. I know you said "rough translation"... – CJ Dennis Jul 03 '19 at 14:00
  • @CJDennis Thanks for the advice. – HDE 226868 Jul 03 '19 at 14:19
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    I@Nzall - It's off the top ironic that Watt's Up With That has used a very incorrectly sited station (a station on a rooftop? seriously?) to claim that this was not the hottest day in France in recorded weather history. The irony is that WUWT has ranted many times over about incorrectly sited stations. People pave paradise and put up a parking lot, and in the process, make what was a correctly sited station suspect. WUWT rants about this, with pictures. They also rant about stations moved due to paradise paving, and unmoved stations that are statistically corrected for paradise paving. – David Hammen Jul 04 '19 at 06:03
  • Not ironic- they were compare actual measured temperatures as against massaged data which was the 50 degree result. The consideration of siting is relevant for considering whether it is climate change not whether a place is hot or not. A poor site is still very hot. – user2617804 Jul 06 '19 at 00:13
  • @HDE226868 How do you reconcile your comment "we have no idea if the Saint-Etienne station complied with any modern procedures" with your answer's headline: "The 1930 measurement was taken incorrectly"? – D Krueger Jul 07 '19 at 03:49
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    @DKrueger I think it may have been unclear; the remark meant that we don't know if even a single modern procedure was followed; we know at least some were not, and those are enough to make the measurement incorrect. – HDE 226868 Jul 07 '19 at 04:10
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    Please note that the new official record is now 46°C, same day, in Vérargues ( [source](https://www.lemonde.fr/planete/article/2019/07/19/le-record-absolu-de-temperature-du-28-juin-reevalue-a-46-c_5491182_3244.html) ) – Gwen Jul 22 '19 at 07:42