The WeatherBlog returns at the end of the season and takes a look at the ice saints on this occasion.
Depending on the region, the ice saints fall on gardens that have been planted too early from 11 or 12 to 15 May. The name days of the Catholic saints Mamertus (French bishop, born 400 a.d., various miracles), Pankratius (died in 304 a.d. at the age of 14 as a martyr for the early church in Rome - at that time the youth apparently still had ideals), Servatius (died in 384 a.d. predicted the Hun invasion of Europe, was possibly beaten to death with a wooden shoe.), Boniface (martyred in boiling pitch in 306 a.d.) and Sophia (early Christian virgin martyr, died around 304 a.d.) mark the time of the last frost of a winter according to a number of country proverbs. (Pankrazi, Servazi and Bonifazi are three frosty Bazi. And finally, the cold Sophie is never missing. - No summer before Bonifaz, no frost after Sophie.)
One possible explanation is that the European continent heats up faster and more strongly than the sea in May. A clear warm/cold boundary promotes the development of low pressure, which produces polar cold air advances - and the basil on the balcony is frozen to death. However, the ZAMG is not completely convinced of the power of the ice saints. Temperature data from Austria over the last 50 years shows that frost in May is very rare, unless you go to the mountains, where frost in May is nothing unusual. That's why there are so few gardens at 3000 meters. About a week after the ice saints, the ZAMG then notes a clear accumulation of cold days, with the unimaginative hint that this could somehow be due to the pitfalls of statistics.
MeteoSchweiz has also looked into this topic and found that the ice saints should actually arrive between May 19 and 23 because the date was shifted during the Gregorian calendar reform in 1582. This would therefore be ideal for Austria. Unfortunately, it was not possible to find the ice saints in the temperature data in Switzerland. Regardless of which of the possible time periods you look at, ground frost is no more likely than on other days in May.
Temperature time series and statistics are therefore no clear answer to the ice saints. During its research, the WeatherBlog came across the following depiction of Cold Sophie and theorizes that Pankratius and Co. get a little too stoned and miss their scheduled mission from time to time.
May Powder
We don't want to blame them, of course, as they have been responsible for heavy, late rainfall this year in the form of low pressure system Yvette. Yvette began its life over northern Italy and moved from there towards the Balkans. Along the way, it collected plenty of moisture from the Mediterranean. Yvette in the east and a high in the west produced a strong pressure gradient and a strong northerly flow over Europe. Here is an animation of the wind in 500 hPa on May 15, Yvette is clearly visible. As early as Thursday night, 15 to 25 liters of rain fell in some north-facing areas. The snow line was briefly at 700 m in parts of western Austria, mostly around 1500 m. This was good for a few late powder turns and the base in the high mountains, but less pleasant for some flood regions. From the Salzkammergut eastwards, Yvette caused flooding, mudslides and landslides. In Austria, the damage is minor compared to last year's record floods. However, some Balkan countries were badly affected. The situation is particularly catastrophic in Serbia and Bosnia-Herzegovina.
At least the rain is over for now and the next few days will be summery - Yvette and the ice saints are on their way. The WeatherBlog is also saying goodbye for the season, which is not to say that the season is over!
