Although he slipped one place on the general classification behind third place finisher Pierre Rolland (Europcar), Kelderman took fourth on the stage and pulled to within 45 seconds of a podium place overall.
"The final climb suited me really well, and after a number of attacks by others, I felt that I was one of the strongest in our group. I accelerated and distanced the rest easily. Then I just kept going until the line."
Kelderman, 23, distanced the likes of deposed race leader Rigoberto Uran (Omega Pharma-Quickstep) and former maglia rosaCadel Evans (BMC) on a day where the peloton was severely tested by snow, rain and temperatures near freezing on the high mountain passes of the Gavia and Stelvio.
"It was a very special day," said Kelderman. "I'm happy you don't often experience days like this. The climb of the Gavia was not too bad, but during the descent, it started too snow very heavily. It was terribly cold and my hands felt like lumps. It was dangerous, as well, because I could no longer see through my glasses."
The race was impacted by a miscommunication between race organisers and the peloton, with stage winner and new race leader Nairo Quintana (Movistar) riding away on the descent of the Stelvio with Rolland and Ryder Hesjedal (Garmin Sharp), while some teams believed the descent was meant to be neutralised by the race officials.
"While climbing the Stelvio, I warmed up again. At the top, I took my time to put on a raincoat as the jury had announced that the downhill would be neutralised. When I made my way back to the main group, however, Quintana, Hesjedal and Rolland were gone. Looking back on that, it's a bit unfair because I wouldn't have stopped if I hadn't heard about the neutralisation. Rolland is now ahead of me in the overall. Normally, I think I could have followed him."
Despite losing one spot, Kelderman is hoping to keep his place or leapfrog over a few riders before the race is over on Sunday.
"With a little bit of luck you can move up quickly," Kelderman said. "But everything is still possible. A top ten remains my main goal."