The 24-year-old said she ran "for her life" to finish ahead of Slovakia's Anastasiya Kuzmina, who narrowly beat France's Anais Bescond for the silver in blustery Pyeongchang.
Dahlmeier, who won five gold medals at last year's world championships, can bring her Olympic haul to three golds if she triumphs in the mass start on Saturday.
"It was really cold and on the shooting range we had a lot of wind," she said.
She added that she felt tired even before the race in freezing and windy conditions.
"I don't know what to say because I felt really, really tired before the race and also during the race in the first laps," she said.
"It's the same in any pressure race because you have to stay focused on your own targets and I think I am a little bit of a master of perseverance.
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