The speaker has no barber and trims their own hair a little at a time, every day. They admit it's a kind of compulsion, something they do without quite choosing to. It sounds like a small, private habit, maybe a nervous one.
Then the poem turns on the word "but." The speaker asks us to look at hair differently: as it ages, it becomes "so quiet a weather." That's a surprising image. Hair isn't just something to be tamed. It's like a mood in the air, soft and slow-changing, maybe grey and calm like an overcast sky.
The feeling here seems to be a mix of restlessness and quiet acceptance. The daily cutting suggests a need to control something, but the closing lines notice a gentle beauty in aging that can't really be controlled. The mood is hushed, reflective, and a little tender, as if the speaker is looking in the mirror and finding peace there.