The couple will marry in St George’s Chapel at Windsor Castle on 19 May, and the 2,640 members of the public invited to the grounds of the castle will unlikely need umbrellas.
Judging by past statistics for May, Sky News weather presenter Isobel Lang believes the date is a good choice for the couple, despite British weather being too erratic to look far ahead with certainty.
She said: “Looking at the daily weather information for Heathrow over the past 20 years, we should see a dry day on Saturday 19 May 2018 with temperatures of 19C, 66F.
“The 20 year dataset from 1998 to 2017 shows that most May 19ths were dry. The wettest one was in 2006 when 3mm of rain fell.”
The average temperature for 19 May is 19C and the date has seen some unusually warm weather.
Temperatures peaked at 26C in 2014 and reached 24C in both 1998 and 2004.
Lang added: “If you look at the monthly average for May, data from the Met Office shows that the average would be around 17.9C – so statistically temperatures on 19 May are a little higher than average.
“It is interesting to note that the monthly average rainfall is around 50mm (two inches) – and somehow 19 May often misses the worst of the rain or showers and stays dry.”
The wettest 19 May was in 2006 when 3mm fell, but most have been dry.
Met Office records state that the average temperature for the month of May is 17.9C.
AccuWeather, a media company that provides weather forecasting services worldwide, predict highs of 17C and lows of 8C for the royal wedding date.
In comparison, the Duke and Duchess of Cambridge’s wedding on 29 April 2011 enjoyed sunny spells and dry weather, despite the threat of showers.