San Francisco’s coastal marine climate, driven by persistent onshore flow from the cool Pacific and a typical August marine layer, anchors trader expectations for a highest temperature of 70–73°F on August 8. Official guidance from the National Weather Service and long-range outlooks place the daily high near the seasonal average of 69–71°F, with the sea breeze and potential fog limiting afternoon warming. The near-even split between the 70–71°F and 72–73°F buckets reflects uncertainty in the precise timing and strength of any clearing or slight offshore component that could add 1–2°F, versus stronger onshore winds or low stratus that would cap readings. Broader regional heat has stayed inland, leaving SF insulated by upwelling and the cold California Current; any last-minute model shift in boundary-layer moisture or wind vector could tip resolution between these two leading outcomes.