Météo-France placed the four Breton departments in yellow vigilance thunderstorms this Tuesday morning. “The first thunderstorms were formed in the morning between Center-Brittany and Trégor, with precipitation that can be abundant and sometimes significant electrical activity. This stormy activity started with the arrival of cold air at altitude and the presence of always quite soft air in the low layers, this is called a cold drop, ”analyzes Steven Tual.
#Ores \ U2614 \ UFE0F \ U26A1 \ UFE0F A stormy sequence in connection with a cold drop will take place between Tuesday and Wednesday with sometimes stationary phenomena.
During the episode, you can expect cumulative 20 to 40 mm (loc. 50-60) with strong runs to wait.#Bretagnepic.twitter.com/4m5pkCSqQ2– Breton weather (@temps_breton) August 18, 2025
“This cold drop will slowly circulate from Brittany to the Center region, which will be conducive to stationary phenomena which can cause strong precipitation very locally. You can have between 20 and 40 mm of rain per hour in a few municipalities this Tuesday, ”says the Breton weather meteorologist. A small possibility of hail exists but “the aggravating phenomenon will remain the stationary rains which can cause streams, even floods”.
#Ores \ UD83D \ UDFE1 \ U26A1 \ UFE0F The thunderstorms are formed in Center-Bretagne, sometimes taking a stationary character. Electrical activity is very concentrated in the Loudéac sector.
Some more mobile thunderstorms circulate on the Trégor.
\ud83d\udd0e RADAR – @KeraunosObs#Bretagnepic.twitter.com/h9N7r5UvnU– Breton weather (@temps_breton) August 19, 2025
If the stormy phenomena will be very “local” on Tuesday, they should generalize next night. “The cells will agglomerate to each other and the rains will be more” effective “, with between 5 and 20 mm on the whole region, perhaps a little less south of Rennes, and locally between 20 and 40 mm between the east of the Crozon peninsula and the black mountain sector”, according to Steven Tual.
Let sun lovers be reassured: “From Thursday, the anticyclone will return with a great weekend, a lot of sun and summer temperatures” à la Breton “, between 21 and 26 degrees”, announces the meteorologist. We will have to take advantage of it because, next week, it is the rain that should take power in the Breton sky.
