The poem starts with a flattering question to the beloved—”Shall I compare thee to a summer’s day?” The beloved is both “more lovely and more temperate” than a summer’s day. The speaker lists some negative things about summer: it is short, rough winds in summer disturb the buds, sometimes the sunshine makes the temperature too hot and other times sun often hides behind clouds.

Then the speaker makes a generalization that everything in nature including the seasons and even people degenerate. However, the beloved has the beauty that will last forever, unlike the fleeting beauty of a summer’s day. By putting his love’s beauty into the form of poetry, the poet is preserving it forever. The lover’s beauty will live on, through the poem which will last as long as it can be read. 

Shall I compare you to a summer’s day? You are more lovely and more moderate: Harsh winds disturb the delicate buds of May, and summer doesn’t last long enough. Sometimes the sun is too hot, and its golden face is often dimmed by clouds. All beautiful things eventually become less beautiful, either by the experiences of life or by the passing of time. But your eternal beauty won’t fade, nor lose any of its quality. And you will never die, as you will live on in my enduring poetry. As long as there are people still alive to read poems this sonnet will live, and you will live in it.