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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
    Commented Jul 3, 2019 at 1:18
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    Looking at a ten-minute record for Gallargues-le-Montueux on 28 Juin 2019 the highest figure seems to be 44.2°C at 16:40 rather than 45.9°C
    – Henry
    Commented Jul 3, 2019 at 7:46
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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
    Commented Jul 3, 2019 at 9:41
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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 en.wikipedia.org/wiki/…
    – Douglas Held
    Commented Jul 3, 2019 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
    Commented Jul 4, 2019 at 6:04

1 Answer 1

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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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    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.
    – David Hammen
    Commented Jul 3, 2019 at 1:09
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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.
    – David Hammen
    Commented Jul 3, 2019 at 1:24
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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, 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
    Commented Jul 3, 2019 at 8:12
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    @gerrit Jwenting is mistaken. There's a report on Facebook from a NonProfit (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
    Commented Jul 3, 2019 at 11:40
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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
    Commented Jul 4, 2019 at 6:03

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