Suspense is built into "All Summer in A Day" from the beginning. It starts with the children asking questions: "Ready? ... Now?" that make us wonder what they are waiting for. We soon learn that it rains all the time on the planet Venus, and, like the children, we as readers long for the brief hour when the sun will soon shine for the first time in seven years:

All day yesterday they had read in class about the sun. About how like a lemon it was, and how hot.

As we enter imaginatively into the lives of these children, we are in suspense about how they will react to the sunshine they have no memory of having ever seen. Then, after the children lock Margot in the closet right before the sun comes out, we wonder if she'll be released in time to see the sun, as we know she has been longing to do. At the end, when the children go to release Margot after it is too late, Bradbury slows down the action to build our suspense about what has happened to her:

They walked over to the closet door slowly and stood by it. Behind the closet door was only silence.

These pauses build suspense. All through the story, Bradbury has prepared us to anticipate what will happen next.