Madrid in August is a city that defers. Shops close from two to five. The terrazas under the awnings on Calle Huertas don’t really open until eight. And the long, dignified plane-tree avenues of the Retiro — the ones that make the park feel like a piece of nineteenth-century Paris transplanted east — are walked, by anyone who actually lives here, between sunrise and about nine-thirty. After that the heat is real and the shadows shorten and you go inside.
Retiro’s geometry helps. The Paseo de la Argentina and the Paseo de las Estatuas run north–south, planted on both sides with mature London planes that arch and meet overhead. At 7 AM the sun is still low and east; the western edges of those avenues hold deep shade until well past nine. The Palacio de Cristal, tucked in the southwest, sits in its own pool of cedar shadow until ten — the only structure in the park that throws useful shade.
The picks below are graded for the early window. None is longer than a kilometer; the idea is to string two or three together with a coffee in between. A practical note: the Puerta de Alcalá gate is the natural entry from the metro but the Felipe IV gate, on the west side, puts you onto the planes faster. Stay Cool will pick the right one.