An extremely cold day is waiting on Wednesday, 22. September 2021 countries of Central Europe and Balkan.
Maximum temperature should reach in basins and valleys only +3/+8°C and very rarely – mainly in Eastern Carpathians, should appear the first snowing of the season below 1000 MASL.
In the lowlands will be warmer, mostly around +10°C (8/12), rarely up to +14°C in large parts of Poland, Slovakia, Czechia, Austria, Hungary, Serbia, Romania, Slovenia, continental Croatia, eastern Switzerland, western Ukraine, or the southern half of Germany.
Around 6:00 will be air in 850 hPa below 0°C located above eastern Poland, northern and eastern Slovakia, large parts of Ukraine and northern Romania and just in these regions, the first snowfall of the season below 1000 MASL is locally possible.
In the Alps, 1 meter of snowfall is expected /https://mkweather.com/heavy-snowfall-1-meter-in-the-alps-is-coming-many-resorts-are-already-under-the-snow//.
Cold air is shifting above the region from Scandinavia, the Baltic region, and Poland /https://mkweather.com/the-first-snow-in-carpathians-lodz-poland-lowlands-almost-frost-07c/; https://mkweather.com/northern-sweden-with-81-cm-of-snow-stockholm-the-first-frost-of-the-season/; http://mkweather.com/the-arctic-blast-will-be-peaking-on-wednesday-snowing-around-800-masl-maximum-temperatures-3c-and-morning-frosts-in-european-mid-latitudes// and will continue above southern Balkan, Greece, Turkey, and Cyprus, where many people on vacation will be surprised by unseasonably cold (or rainy) weather in the second half of the week.
Cold air will gradually shift eastward until Friday, 24. September 2021 and from the weekend, a period of Indian summer will be beginning /will be updated already in the next Mkweather article; https://mkweather.com/the-first-phases-of-indian-summer-in-europe-already-between-25-september-5-october-2021//