The coldest/hottest you could possibly get in a calendar month.

[WYorksWeather]

 LetItSnow! It's certainly a ridiculous chart. Obviously odds are very low of it verifying on this one occasion, but at some point one of these excessively hot plumes will find the mark with the right surface conditions, and it'll smash records here just as the previous one did across much of Central Europe.

It doesn't quite meet the 20C average for 24 hours I mentioned, but it'd certainly average 17-18C, which is right at the top end of what I thought would be possible for April.