On a clear day in June the terrace has sun 13:20–15:20, about 2 hours in total.
The story of Koh Phangan
Koh Phangan on Nybrogatan is the Östermalm sibling of the Thai restaurant on Skånegatan in Södermalm, which opened in 1994. The idea was born on a beach on the island of Koh Phangan off Thailand's east coast, with the aim of serving up a small trip to paradise.
When the restaurant started out, Thai vegetables, herbs, beer and spices were not available in Sweden, so everything was imported directly from Thailand. The restaurant says its whole interior was brought home from there, with considerable effort.
Sources: Koh Phangan Östermalm · Koh Phangan Södermalm · Routes North: Koh Phangan (mentions the Östermalm branch)
How Stoligt works it out
Every ten minutes we draw a line from each terrace toward the sun and check whether a building or hill is tall enough to block it. Building heights come from OpenStreetMap and ground heights from Lantmäteriet, the Swedish mapping agency. The times assume a clear day, so clouds are not included here. They are on the live map, which shows today's weather.
Trees, parasols and awnings are not in the model, and we don't know exactly where on the pavement the tables stand. Treat the times as an educated guess, often accurate to within ten minutes.