England without several key names for USA and Switzerland friendlies
Wiegman will also be without Manchester United midfielder Ella Toone due to a calf injury, plus Chelsea duo Lauren James and Niamh Charles with calf and shoulder problems respectively, and Aston Villa defender Lucy Parker with an ankle injury.
"That's part of football, and unfortunately you want the best team or the best players in your squad all the time, but sometimes players are injured or not available for a reason, and then other players have the opportunity to step up and show, that's how we approach it all the time," Wiegman said.
While Manchester City did not elaborate on the severity of Hemp's injury, Wiegman said it is not a torn anterior cruciate ligament.
Asked about the extent of Toone's calf injury, Wiegman said that was a question for her club.
The absences mean Manchester City's Laura Blindkilde Brown and Leicester's Ruby Mace earned their first senior call-ups and United defender Gabby George is back after a two-year absence.
"Young players, very talented players," Wiegman said of the two debutantes.
"Competition at Manchester City in midfield is tough, but Laura gets minutes. They've done well at under-23s and this is an opportunity, I hope they compete straight away.
"Very happy for (George), she's worked so hard," Weigman added.
"She's done very well at Manchester United. She's showed some pretty good games recently."
England have already qualified to defend their title at the European Championships this summer in Switzerland, and are using the friendlies as preparation.
USA team manager Emma Hayes is also missing key forwards Trinity Rodman, Sophia Smith and Mallory Swanson, due to injuries.
England host the USA at Wembley on November 30th, and Switzerland at Bramall Lane on December 3rd. The USA also play the Netherlands in a friendly at The Hague on December 3rd.
Wiegman's side defeated the Americans 2-1 the last time the two teams clashed at Wembley, in October 2022, thanks to goals from Hemp and Georgia Stanway.
England squad:
Goalkeepers: Mary Earps, Hannah Hampton, Anna Moorhouse.
Defenders: Millie Bright, Lucy Bronze, Jess Carter, Gabby George, Alex Greenwood, Maya Le Tissier, Esme Morgan, Millie Turner, Leah Williamson
Midfielders: Laura Blindkilde Brown, Grace Clinton, Frank Kirby, Ruby Mace, Jess Park, Georgia Stanway, Keira Walsh
Forwards: Aggie Beever-Jones, Chloe Kelly, Beth Mead, Jess Naz, Alessia Russo