Austria -8,3°C, the UK -7,3°C, Germany -6,4°C, France -5,6°C, Croatia/Bosnia -5,0°C, the Spain -3,8°C
Marek Kučera 
Another cold morning hit Europe from British Island to western Balkan and we should recapitulate Friday´s 16. April 2021 TOP national minimum temperatures from International Exchange Database.
The coldest air is slowly shifting eastward and southward and record cold was on Friday according to coolwx.com weather tool mainly in the UK, France, Germany, Austria, Italy, Croatia and Bosnia and Herzegovina.
There are only data from main stations, therefore, even colder minimum temperatures from valleys or basins, mainly from Alpine region (below 1000 MASL) are possible – very probably between -10/-15°C locally.
The coldest air according to database already shifted above Austria – Achenkirch in 932 MASL reported only -8,3°C.
The second coldest report is from Aboyne, the UK, again, with minimum temperature -7,3°C. Scottish settlement is situated only 140 MASL and frosts are reported from here already 16 days in a row (16 consecutive days with frosts in April 2021) /https://mkweather.com/parts-of-the-uk-with-15-day-consecutive-frosts//.
The third place belongs to Germany – surprisingly strong frosts hit Munich, with only -6,4°C on Friday´s morning. For metropolitan city it should be serious temperature shock – lastly hit stronger frosts Bavaria only in February 2021, when central parts of Germany reported 30-degree frosts.
Extreme frosts furthermore bother France – many cities according to coolwx,com reported on Friday again new daily temperature records. The coldest was in Le Puy, 832 MASL, only -5,6°C.
Extremely cold weather has returned into western Balkan – Gospic, Croatia, 564 MASL and Livno, Bosnia and Herzegovina, 724 MASL reported identically -5,0°C. Frosts in the region during the first April decade however were stronger /https://mkweather.com/belgrade-10-cm-of-snow-new-record-of-the-latest-snowfall-since-1888-croatia-120c-in-564-masl/; https://mkweather.com/european-april-arctic-blast-206c-in-718-masl//.
The last interesting observation came from northeastern Spain – station Polientes Casyc, 720 MASL reported on Friday only -3,8°C, what should damage local harvest.
Eastern parts of Central Europe, Balkan and Baltic states for strong frosts are only waiting and they should hit already at the weekend after period with regional late blizzard /https://mkweather.com/bakony-hungary-30-cm-snowfall/; https://mkweather.com/snow-calamity-in-southern-poland/; https://mkweather.com/peak-of-winter-2020-21-in-april-near-bratislava-has-fallen-24-cm-of-snow-border-region-slovakia-poland-czechia-with-30-40-cm//.
During the third April decade, frosts 0/-5°C are forecasted to come back /https://mkweather.com/europe-hits-in-the-3rd-april-decade-the-next-coldwave-speculations-about-may-2021-cold-april-may// in Europe and the start of May 2021 should surprise according to the newest materials with widespread ground frosts, or light frosts regionally.
Marek Sadowski 
