Ria, I remember the Ice Saints from my time in Germany... in 1975 I was at RAF Laarbuch on the Dutch border and we had a late spring, but then we had the most brilliant summer. We can hope, sorry Jo.
Here in the UK we have "Ne'er cast a clowt till May be out". It apparently relates to May (Hawthorne) blossom, and the cooler it is the later it appears - in May (the month). It is struggling this year.