The forecast makes interesting reading. The 'public' forecasts seem about as much use as Mystic Meg.
One of the issues that has to be taken into account regarding the weather in the UK is the influence of the jet stream. This zig-zags round the globe at our latitude. On the south side you get warm weather and on the north, cold. The stream of wind is quite narrow but it pulls in the weather alongside it.
So, if the jet stream shifts to the south, we tend to get cold wet weather with more northerly winds. Similarly, if it shifts north, the weather tends to come from the south or south west (Caribbean, gulf stream) making it warmer.
All of this gets you not very far except that the sun has an 11 year cycle (sunspots, etc.) which when it peaks, increases the heat hitting the earth by just enough to cause the jet stream to shift north, and at its minimum shifts it south.
We have just passed the minimum and should see a peak in 2013. It won't be a big peak in 2013.
If you want more information on the solar cycle, see
http://science.nasa.gov/science-news/science-at-nasa/2009/29may_noaaprediction/NN