“We might see the temperatures reach the upper 80s in downtown Oakland, and for San Francisco, we might get into the mid-80s,” Hoang said. By Tuesday, inland areas such as Walnut Creek could reach the low 90s. The high-pressure system forming isn't the same as the type that creates record-breaking heat, but it will still likely push the marine layer farther out to sea, allowing for offshore winds to bring hotter days to the region.