As we all know, the British weather is all but predictable. However, did you know that there are 'singularities' or periods of weather with fairly predictable patterns and generally high confidence of that prediction?
Have a look at the very clever Metcheck website: metcheck weather singularities
It is interesting (and perhaps encouraging) to see that the last half of May is traditionally warm and settled (88% confidence) and we are in a predictably cool period where westerlies are rare. The chart on this page does make interesting reading but I'd still be nervous about planning a holiday around it!