England has a collected data on daily temperature from 1772 in the Hadley Centre Central England Temperature (HadCET) dataset.
Here the black line is the average temerature for each day last year. The dark line in the middle is the average average temperature (95% confidence). the staw coloured bigger lines represent the highest and lowest average daily temperature ever recorded on that day since 1772. the red dots are the days in 2015 that were hotter than any other day at that time of year since 1772.
Looking at the black line that represents last years temperatures it was the Winter and Autumn that were far above average. Instead of a scorching hot summer most of the record hot days were in November and December. 2014 had the same pattern of a hot Winter. No day in 2015 was the coldest for that date in the recorded time.