Britain's Prince William accompanied by his fiancee Kate Middleton, arrives at Witton Country Park, Darwen, England, Monday April 11, 2011. Prince William and Kate Middleton will marry on April 29. (AP Photo/Tim Hales) (Tim Hales/AP)

Although it’s certain to become cooler than it has been in recent days by the middle to late part of this week, forecast details remain murky. The big question: will it be dry or wet? Rain and umbrellas would complicate pre-wedding photo opps outside Westminster Abbey. And it would rule out an open top procession back to Buckingham Palace after the ceremony writes the Daily Mail. Instead, the newly wedded couple would be transported in a covered glass coach.

The Telegraph quotes one forecaster calling for the “risk of heavy showers.” Another forecaster quoted by the Telegraph predicts “a risk of showery rain”, but says there will be “occasional brighter spells.”

The United Kingdom Met Office has a website dedicated to Royal Wedding weather and posted the following “official” forecast:

In the London area, there will be some rain through the early hours, but this should clear to leave a cloudy but drier morning. Some bright or sunny spells may break through, possibly leading to further showers. A brisk northeasterly wind could make it feel rather chilly whenever the sun goes in.

I’ve got one suggestion for UK Met Office: include a temperature forecast!

My analysis of forecast models are consistent with these predictions for variable cloud conditions and a 30-40 percent chance of showers. While no organized weather system will be positioned to produce an all-day, soaking rain, these models show the United Kingdom wedged between high pressure to the northeast and low pressure to the southwest. That will result in a northeasterly flow off the North Sea which may support some occasional, scattered showers. But more often than not, it should be dry.

Temperatures look to be a good 15-20 degrees Fahrenheit (or 10 degrees Celsius) colder than they were over the Easter weekend. That means highs from the upper 50s to low 60s (14 to 16 C) - which is right around average.

For a good part of April, London has been treated to unusual warmth. The Guardian reported Sunday the April is on track to be the hottest on record in London. Over the Easter weekend weather, highs reached the mid-70s to around 80 degrees (25-27 C)

Related post, from November 24, 2010: Weather forecast for royal wedding now, seriously?.