The 23-year-old earned her first career silver and second total medal by finishing second in the 5,000-metre race with a time of seven minutes, 6.19 seconds. That left the Ottawa native exactly one second behind gold medallist Esmee Visser of The Netherlands.
Canadian Ivanie Blondin finished just over half a second off of the podium (7:10.22) behind bronze-medal winner Natalia Voronina of Russia.
Watch Weidemann's silver-medal skate:
Weidemann won the first medal of her career — gold — in the 3,000 in Tomokomai, Japan, two weeks ago.
"I feel very happy with my race today," said Weidemann. "My goal was to stick to consistent lap times and I feel like I executed that. I've been nervous the past couple of weeks, after winning in Japan, because I wanted to prove that my result wasn't a fluke. I have lots to work on still, but I'm excited for the opportunity to race next weekend in Heerenveen."
In other results from Poland, Canada finished sixth in the ladies' team sprint, 1.89 seconds behind the winner. The men's team sprint quarter placed last, over 26 seconds behind the pace.
After kicking off her long track World Cup career with a seventh-place finish in Saturday's Division B 1500m, Valérie Maltais of Saguenay, Que. came second in the Division B ladies 5000m with a time of 7:17.628.
She will get the opportunity to test herself against competitors from the top grouping in that distance at next week's World Cup.
"I was nervous coming into this race because I was scared of the pain that comes with a 5000m," said Maltais with a laugh. "The ice was difficult here because it doesn't slide much, but I was able to adapt and followed my game plan the best I could. Overall, it was an excellent debut for me."
Toronto's Jordan Belchos finished in 12th position in the men's 10,000m, skating in 14:03.795. Meanwhile, Graeme Fish of Moose Jaw, Sask. earned a third-place result in the Division B race at 13:20.562. Calgary's Ted-Jan Bloemen finished 10th (13:38.552) in that same grouping.
"This was definitely the best 10,000m I have ever skated," said the 21-year old Fish, who was competing in just the second World Cup of his career. "Technically it was very good. I could build the turns really well and my position stayed the same the whole race."
Watch full replay of Sunday's action in Poland: