The organization tasked with transporting them to a California sanctuary says the summer heat is too much.
"We're in the middle of a heat wave and because the crates are made of steel and there's some radiant heat potentially. Although the aircraft itself is temperature controlled, you know when the animals are on the tarmac and there's clearance and so on that has to go on, just for safety sake we've decided that we're going to look at September," said Julie Woodyer of Zoocheck Canada.
The original date to ship Iringa, Toka and Thika south was set for Aug. 2.
Animal rights activist Bob Barker has offered to pay for the transportation.
With specialized crates, a team of vets and experts, and the use of a large Russian aircraft, the trip has an estimated price tag of $1 million.
View our gallery of Toronto Zoo Elephants provided by PAWS/Zoocheck Canada