In just three lines, the poem puts us inside a moment of strange helplessness. The speaker looks at an arm made of ice, or turned to ice, and finds it cannot be moved. The arm is called "small," and the speaker calls it "which I am / not able to stir," so it is both theirs and somehow out of reach, like a part of the body that has stopped answering.
The comparison "white as noon" is surprising, since we usually think of noon as bright and warm rather than cold. Here the glare and the frost blur together, which fits the title: a whiteout, where everything disappears into sameness and you lose your bearings. The mood is quiet, stunned, and a little eerie. The speaker doesn't shout or panic. The calm, plain voice makes the paralysis feel more unsettling, as if the speaker is simply noticing what has happened. The poem leaves open whether this is literal cold, a dream, or something more emotional.