The Colorado Street Bridge throws a 200-meter shadow across the Arroyo Seco floor by 3 PM on a summer afternoon. Combined with the original sycamore-and-live-oak riparian canopy, the floor of the arroyo runs 12 to 15 degrees cooler than the residential streets above. The trick is getting in and out — the descent paths on the east side hit sun on the upper switchbacks but recover within 100m of the floor.
These three pick the cool descents. The Vista del Arroyo Hotel descent is the deepest immediate shade; the Salvia Canyon trail off Linda Vista is the longest continuous canopy. We avoid the trail spur that crosses the dry creekbed at noon — full sun, no thanks.