Edward Thomas begins at the end of the day, once the weather has done its worst, with a modest conclusion: "Now I know that Spring will come again, / Perhaps to-morrow." The small hedge matters. The knowledge is real, but "perhaps" stops it from becoming a boast. The rest of the poem shows how the speaker got there, and the route is stranger than we expect. The answer comes not from a sign of spring but from the silence that follows a burst of birdsong.
The first movement is a day of punishment. The speaker's temples ache "from the cold burning / Of hail and wind," and the primroses lie "Torn by the hail," buried in it. Then the sun breaks through, and the poem allows itself a tender image: where the hail drips, there is "almost warmth," "As if the mighty sun wept tears of joy." It is the old habit of reading nature's weather as feeling, and Thomas lets it stand for a moment before cutting it off: "But 'twas too late for warmth." The sunset piles "Mountains on mountains of snow and ice in the west," clouds turned into a range where the wind gets "lost" in the folds. Then comes the poem's most careful sentence: "I knew that Spring / Would come again, I knew it had not come." Those are two kinds of knowing, one a settled belief and the other a plain report of how cold it still is. The poem refuses to let either cancel the other.
The turn to the thrushes begins with a real question, "What did the thrushes know?", which the speaker does not claim to answer. The weather has kept the birds "quiet as the primroses," so the flowers and the singers suffer alike. Their song is a race against the light, since they have only an hour "before the moon / Grew brighter than the clouds." The syntax hurries with them: "On boughs they sang, / On gates, on ground; they sang while they changed perches / And while they fought, if they remembered to fight." That last clause is quietly funny, and affectionate. The birds are so busy singing they can barely spare time for quarrelling. Their "unwilling hoard of song" is a lovely paradox. A hoard is something saved up, and here it has been held back by the weather and is now forced out. They sing "hoarse or sweet or fierce or soft," and even "screamed," yet the speaker's verdict is generous: "they could do no wrong."
The form suits this. The poem is unrhymed and loosely iambic, closer to blank verse than to anything ornamental, and sentences run past line endings the way thought does in speech. Thomas also uses the rhythm for effect. In "Rain, snow, sleet, hail" the commas force a stop after each heavy word, so the weather lands like four blows. The long, tumbling sentences about the thrushes then give way to something much quieter. The poem's shape is circular. It opens with a conclusion and closes by repeating it, but the repeated line now carries the weight of everything between.
The ending is the poem's real achievement. "Something they knew—I also, while they sang / And after." Thomas never says what the something is. Only when night has "half its stars / And never a cloud" does the speaker become "aware of silence / Stained with all that hour's songs." "Stained" is an unexpected word. It makes silence a cloth that has soaked up the songs and kept their mark, so the quiet itself becomes a message: "Spring returns, perhaps to-morrow." The "perhaps" survives to the last line.
That restraint is why the poem matters. It could have been a cheerful greeting to spring, but it is about hope kept up while spring is still absent. The title names a month famous for turning from sun to hail within hours, and the poem sets its trust there, in the uncertain weather. Its comfort is small and earned. It comes from noticing what a hurried, ragged hour of birdsong leaves behind, and from the patience of a speaker who can wait for "to-morrow."