Persistent onshore flow and a stubborn marine layer stratocumulus deck over coastal Southern California are anchoring Los Angeles International Airport highs in the mid-to-upper 60s on May 16, producing the near-even split between the 66-67°F and 68-69°F bins. Cool sea-surface temperatures sustain overnight cloud cover that delays peak solar insolation, capping boundary-layer mixing below the May climatological normal of roughly 69°F. National Weather Service guidance and ensemble runs from GFS and ECMWF show only modest spread in afternoon mixing depth, with lighter winds or earlier burn-off favoring the upper bin and prolonged deck persistence tilting toward the lower one. Overnight model updates and final observations will resolve the narrow range before the market settles.