We've had 56 days above 20C here so slightly more than 15% of days this year were above 20C. We had 1 in April, 0 in May, 13 in June, 17 in July, 23 in August and 2 in September. June and August were both around normal, July and September were very disappointing. May was astonishingly bad. Getting 20C in April and October isn't guaranteed every year, but in May it certainly is.. until this year.