The opening phrase, "On longer evenings," establishes that the poem is set during the onset of spring, a time of year when the days start to grow longer as the sun sets later and later. This setting reflects poem's title, "Coming," which subtly hints at a sense of newness and change, as spring is "coming" to replace winter.
The speaker goes on to describe the quality of sunlight on these early spring evenings, calling it "chill and yellow." The fact that the sunlight is still "chill" suggests that winter has not yet fully passed, since the light remains cold even though it's around for more hours in the day. The days may be longer, then, but they are not yet warm; there's the appearance of spring without the genuine feel of it—a setting that, in turn, foreshadows the speaker's ideas about the shallow nature of springtime hope.
All the same, the light still "bathes" the houses, which themselves are "serene." The speaker uses personification in this moment, referencing the "foreheads" of the houses and depicting them as people who are calm and subdued. The imagery of sunlight washing over "serene" houses suggests that the light will perhaps reawaken the houses, which have been sitting somberly throughout the winter. Here, at least, spring is portrayed as a source of renewal and rebirth.
Despite the seemingly uplifting subject, the speaker's overall tone is unenthusiastic. Not only are the speaker's descriptions tempered by the mention of coldness and a certain feeling of somberness, but the actual rhythm of the words has a somewhat defeated sound. This is because three of the first four lines all end on unstressed syllables. "Coming" is not written in meter, but there's no question that the last words of the first, second, and fourth lines have a stressed-unstressed pattern:
This pattern creates a falling sound that hints at a sensation of melancholy—one that doesn't align with the otherwise joyous feelings that people associate with spring. As a result, readers will perhaps pick up on a subtle kind of cynicism that will run throughout the poem, starkly contrasting the supposedly happy tidings of springtime.