C is for ........ Cork and champagne

If you think I have cracked open the bubbly a bit early, you are wrong I'm afraid. The bottle and cork are keepsakes from my wedding and the glass contains sparkling apple juice. I did a shot very similar to this for the 'Celebrations' project at photo group over the summer, they seemed to like it, so I thought I would have another go at it.
I have spent most of the day totally engrossed in a quiz that has been set by my mum's WI and she is finding it quite hard so she asked me to help and I have to say it's one of the toughest quizzes that I have ever done. It has been very cleverly written so that most of the questions are not easily searchable online (a dastardly trick), and I refuse to admit defeat so it's driving me mad. Does anybody know in what UK town there was a fluctuation of 21 degrees C over the space of 1 week at the end of March/beginning of April 2012? I remember it well but I cannot remember the name of the town and I can't find out anywhere, can anyone put me out of my misery :-)