FILE – In this Nov. 16, 2010 file photo, Britain’s Prince William and his fiancee Kate Middleton pose for the media at St. James’s Palace in London, after they announced their engagement. (AP Photo/Kirsty Wigglesworth, File)

The Royal Wedding is less than a week away, and while temperatures will be favorable , clouds and rainfall could dampen the big day.

Over the past week, temperatures have reached 27 degrees C (81 F) in and about London, where normal high temperatures are about 14 to 15 degrees C (57 to 59 F). This warmth represents temperatures significantly above even those typically seen in midsummer.

So far this month, unusual warmth has spread over much of England and northwestern Europe as a whole. April temperatures at London’s Heathrow Airport have been an average of 5 degrees C (9.0 F) above normal, potentially on track for a historic high for the month of April.

The present summery warmth has been the product of far-reaching high pressure. However, with high pressure often comes strong temperature inversions, which can bring air pollution headaches.

On Friday, smog settled over London and remained there through the weekend, which lead to air pollution advisories.

Early in the week, a cold front will allow temperatures to settle back somewhat, helping to stir up and sweep away pollutants, improving air quality.

This cold front will be short-lived, as high pressure anchoring over Scandinavia will again dominate the weather across northern Europe, including the U.K., as temperatures creep back above normal for the middle of the week.

As for the wedding forecast, the April 29 nuptials in London will take place amid a backdrop of seasonably comfortable temperatures.

Low clouds will start out the day, then skies will become mixed with breaks of sunshine. A few showers may move through the area, but odds are against any long duration rainfall.

Moderate breezes from the east and northeast will accompany temperatures reaching 16 to 18 degrees C (60-65 F). The breezes should prevent the return of any smog.

AccuWeather.com Staff Writer Gina Cherundolo contributed to the content of this story.