Leclerc had a collision with Oscar Piastri on the damp first lap of the race before diving into the pits for a switch to intermediates, which proved to be slow as the crew wasn't ready with his tyres.
The team could do nothing about the damage to his floor, and data indicated that he gradually lost more downforce as the race progressed.
He tumbled down the order and, shortly after being demoted to 16th by rookie Liam Lawson, he was called in to retire the car.
Although it did rain again late in the race, it wouldn't have helped Leclerc's cause by that stage.
"Already at the first lap when we had the damage I could feel much more than the guys were telling me on the radio," he said.
"Initially it was five to 10 points [of downforce] was what I've been told, but obviously then we realised it was more than 60, and more than 60 is a different category. After that, after the first lap, it was all uphill.
"We were just waiting for some rain, to be honest. Obviously, it's very tricky to drive a car with 60 points less in the rain, but it also adds a lot of chaos, and you can do something different than others and maybe score one or two points.
"Every point counts, so we didn't want to give up too early. Then we understood that the rain wouldn't come, even though now it came, but it would have been too late."
Source: Autosport