A year in the standards. This is what emerges from the analysis of meteorological data in the Loire for the year 2021.
Sunshine: a not so overcast sky
By only retaining the months of January and November 2021, which show respectively 47% and 33% of sunshine deficit, we could have found the year 2021 particularly dull. And yet! The star of the day shone for 1,891 hours on the Météo France station of Saint-Etienne / Bouthéon. The luminosity of the year is therefore within the standards with a deficit of only 5% compared to the normal. A situation that can be explained by a particularly bright spring and autumn: 14% excess sunshine in April and 32% in October. Conversely, the summer months are in deficit, with up to -22% light in July.
Slightly deficit precipitation
On the precipitation side, a slight deficit was recorded: 661.8 millimeters of rain at the Saint-Etienne / Bouthéon station against 718.2 millimeters for a so-called “normal” year (ie 8% deficit). However, the rainfall year saw a sawtooth with a very dry March (66% rainfall deficit) and, conversely, a very rainy month of July (+ 51%). Note also a month of November which, although particularly gray, was not rainy since it shows a rainfall deficit of 63% compared to a normal month.
However, a record was set in terms of rainfall: on Monday, May 10, 73 millimeters of rain fell in the space of 24 hours. Never had a day in May been so rainy (the previous record dating from May 23, 1959). By way of comparison, the absolute precipitation record on this station dates from Tuesday, November 12, 1996: 97.4 millimeters in one day!
On the other hand, the strongest gust of the year (93.6 km / h) was measured on Saturday, October 30.
Temperatures: no excess
On the mercury side, with an average temperature of 11.3 ° C, the year 2021 ranks 0.1 ° C below normal.
The highest temperature of the year was recorded on Saturday August 14: 33.9 ° C. The least cool night was recorded on Thursday, June 17: 20.4 ° C at the “coldest” of the night. More surprisingly, the record for the cold of the year arrived very late, Thursday, April 8, with -7.4 ° C, beating the record for the coldest temperature ever observed on this station for the month of April. The year nevertheless remains far from the maximum recorded in the Bouthéon resort: 41.1 ° C for the absolute heat record of July 7, 2015 and -25.6 ° C for the cold record dating from January 4, 1971.
Sixteen orange vigilances triggered on the department
During the year 2021, the Loire department was placed sixteen times in orange vigilance (level 3 out of 4) by Météo France. This is as much as in 2019, the year in which the Loire was the second French department most often placed on meteorological vigilance. By way of comparison, the Haute-Loire has been placed “only” nine days in orange vigilance over the past twelve months.
In detail, seven days of this year 2021 (in June, July and August) took place under the orange flag due to a risk of severe thunderstorms; four days for a risk of snow and ice; four days also for a risk of strong winds; and finally a day in vigilance due to rain / flood.
However, the number of vigilances triggered in the department does not reflect the observed climate: according to the annual report delivered by Keraunos, the French observatory for tornadoes and violent thunderstorms, the Loire actually records a deficit of days of thunderstorms compared to the average observed over the past twelve years. A trend which is confirmed at the national level since out of the ninety-five departments of Metropolitan France, only eight show an excess number of stormy days. “At the national level, there are 236 days with a thunderstorm in 2021, which is a lower value (Editor’s note of 11 days) than the average of the past 12 years”, indicates the Keraunos observatory.