Both the Duchess of Cambridge and the Duchess of Sussex are attending Ladies' Finals Day at Wimbledon today (July 13).

Kate is patron of the All England Lawn Tennis Club (AELTC), and will join Meghan in the Royal Box for Serena Williams' clash with Simona Halep in the Women's Singles Final.

Saturday marks the pair's second visit to Wimbledon 2019 — Kate made a trip to Court 14 to watch the UK's Harriet Dart, before heading to Centre Court to watch Roger Federer in action.

Meghan's attendance earlier in the tournament caused a small stir after royal protection officers told spectators not to take pictures of her while watching Williams on Court One because she was there "in a private capacity".

Meghan and Williams, one of the most-decorated tennis players in history with 23 Grand Slam singles titles, are close friends, with Williams attending her wedding to Prince Harry last summer.

"She couldn't be a better friend to me. Low moments, high moments, she's always there," Williams said.

"That's all I want to be to her."

Williams is just one match away from equalling the women's record for the most grand slam wins.

The seven-time Wimbledon winner is just one title away from Australian player Margaret Court's record of 24 grand slam career wins, which has stood since the 1970s.

An outing to Wimbledon could become an annual fixture for Meghan and Kate.

Last year, they both visited the All-England Club to see the 2018 women's final between Williams and German player Angelique Kerber.

A spokesman for the Met Office said the duchesses ran the risk of some wet weather.

"There's a fairly good chance that it's going to stay dry but I couldn't rule out a few showers around mid afternoon," he said.

He said there was a 30 per cent to 40 per cent chance of the tournament seeing some rain.

He added: "Other than that it's looking dry and bright with some sunny spells with highs of around 23C (73.4F).