Wesche produced a huge throw on her final attempt, which looked like it could reclaim top spot, but it was ruled a foul.
It was the same pattern as last year’s Paris Olympics, when Wesche led going into the final round, only to be relegated to silver when pipped by Germany’s Yemisi Ogunleye.
Wesche took a positive attitude to the outcome.
“I’m still a little bit speechless, sitting in first place for most of the competition was a little bit foreign to me,” she said.
“To throw 20 metres on my first throw and then over 22 metres on my last [a foul] shows that all the training my coach, my team and I have been doing is paying off.
“I’ve got bigger goals and bigger distances to come, those are my aspirations in this sport.
“This was the craziest competition I’ve ever been part of and those are the moments you live for as an athlete.”
By securing a third medal, Wesche confirmed New Zealand would enjoy its most successful World Championships campaign.
This week Georgie Beamish won gold in the 3000m steeplechase, followed by a podium-topping performance from Olympic champion high jumper Hamish Kerr.
Also in action overnight, Tori Moorby finished an impressive seventh in the women’s javelin final, after qualifying sixth.
Her best throw of 61.53m left Moorby just over 2m outside securing a bronze medal.
Connor Bell qualified 11th for tonight’s men’s discus final.