Meanwhile, Hug, who won the men’s race in Boston, had Romanchuk for company throughout the first half of the race in London.
The pair appeared to have moved clear of the rest of the field but Weir and Japan’s Tomoki Suzuki reeled them in.
However, Hug had enough left in the tank to drop his competitors in the second half of the race to win comfortably.
“It was a really amazing race but it was also really tough. The conditions were tough, there was a lot of wind. I tried many times to break away and it finally happened,” Hug told BBC Sport.
“So many great memories here, some tight finishes. I was lucky today I could go away a little bit earlier. The crowd is always amazing. For us, it’s really amazing.”