According to a Sky press release, the 27-year-old Welshman sustained the fractures during a whitewater rafting trip.
"My brother Matt is getting married and so I was away with family and friends for his 'stag party.'
Rowe has since had surgery on the broken leg and is now home in Cardiff, but now faces a lengthy recovery process. The team did not specify when he would return to racing.
"Obviously it's a serious injury and so Luke's going to be off the bike for a while," said coach Rod Ellingworth. "An injury like this is a test of character for anyone, but character is something Luke has plenty of."
After riding as one of Sky's leaders in the spring Classics, Rowe took on the Tour de France in support of winner Chris Froome, but the four-time Tour victor will be without his teammate's services as he looks to pick up an elusive first career Vuelta a España victory in the coming weeks.