Surface Wind Direction Off California Coast (35°N, 125°W)

At the coordinate 35°N, 125°W (approximately 300 nm west of Point Conception / San Luis Obispo), the prevailing surface wind is from the northwest (NW).

Why NW?

• North Pacific High (NPH): Semi-permanent subtropical anticyclone centered ~35°N, 140°W (summer) / 30°N, 130°W (winter).
• Clockwise Circulation: Around the High, winds spiral outward. On its eastern flank (off CA), flow is from NW to SE.
• Seasonal Shift:
  • Summer: NPH strongest, displaced north → strong, persistent NW winds (15–25 kt). Drives coastal upwelling (cold, nutrient-rich water).
  • Winter: NPH weakens, shifts south → NW winds lighter, more variable; occasional southerly surges ahead of Pacific fronts.
• Thermal Low (Central Valley): Summer heating over inland CA creates a thermal low, tightening the pressure gradient → stronger NW coast winds (the "marine layer" engine).

Mariner's Rule of Thumb

"Nor'westerly" is the default. If it's southerly, a front is approaching. If calm/light variable, the High is overhead or a thermal trough has collapsed the gradient.

Source: COADS/ICOADS climatology, NWS Marine Forecasts (Zone PZZ250/PZZ270), Pilot Charts.