The Salesforce Tower is sixty-one stories of unremarkable glass with one genuinely useful property: between 2 and 5 PM in summer, it puts a long, narrow shadow across most of the eastern half of SoMa. The shadow walks north-northeast through the afternoon, sweeping from Mission Street out to the Embarcadero. If you are downtown and you can time your meeting around it, you can walk in shade for distances that no other building in the city offers.
The picks below are all graded against the actual sun position in late July, when the shadow is shortest and the city is hottest. Earlier in the year the shadow runs longer; the Stay Cool router will recompute it. The one rule: walk with the building behind you and a little to your right. The geometry holds.
The catch is that SoMa is also where the city’s heat-island effect is worst — the surface parking, the wide streets, the wind tunnel off the Bay. So the shaded routes feel cooler by more than the shade percentage suggests. You are also out of the wind.