May 18 is likely to remain the warmest day of the month, as the mercury rose to +27°C for the first time this year.

However, it will get colder over the weekend, with temperatures to drop by 5-7°C.
A high cyclone will replace a high (blocking) anticyclone. The atmosphere will become unstable. There will be powerful cumulonimbus clouds that will bring rain, at times heavy, and thunderstorms.
There will be no significant changes in nighttime temperatures (+10…+12°C). In the afternoon, the mercury will rise to +17…+20°C.