Long range forecasts are based on the probability of a type of weather occuring. This data is compiled from many different computer simulations with slightly different starting conditions for each simulation.
This is very unreliable more than a week or two out, so don't pull all your hair out if it says rain, or jump for joy if it says sun!!
I've copied and pasted some long range forecasts below from various weather websites about July:
July 2008
Although July will start on a promising note, there will still be a fair amount of rain around from time to time, perhaps on the heavy side, and giving cause for concern. After this, we expect the weather to break as the Azores high, (which remained too far south in 2007), begins to build to a more favourable position, to give us a run of fine weather with warm temperatures. July ends on a humid note with the threat of thunderstorms. Temperatures for the month will reflect above average values.
July:
Temperature: Slightly above average
Precipitation: Close to average
The first half of the month is likely to bring rather changeable conditions with some rain or showers affecting all areas at times. Fairly typical conditions are likely, with southern areas seeing less rain and higher temperatures than the north.
During the second half of the month high pressure is increasingly likely to be in control of the weather across the UK, and this should give a good deal of fine and settled weather, especially in southern areas. Northern areas are likely to be less settled with rain or showers at times.
Monday 07 July 2008 to Sunday 20 July 2008:
There appears to be little change in the overall surface pressure pattern with the Azores high still trying to ridge towards southern parts of England and Wales.
Rainfall may again be just above the seasonal average with temperature and sunshine amounts only average for early to mid-July
looks promising!, but how reliable are these long range weatherforcasts? I hope its spot on!
