Half Moon Bay, CA Climate

Climate Insight: Half Moon Bay, CA

In Half Moon Bay, California, the NOAA 1991–2020 climate normals put the annual average temperature at 55°F, ranging from a mean daily high of 63°F to a mean daily low of 47°F. August is typically the warmest month of the year, while December is the coldest. As thirty-year averages computed from station USC00043714, these numbers smooth out year-to-year noise into a working baseline for a typical month.

Rainfall (and snow, where it falls) shapes day-to-day life here as much as temperature does. Half Moon Bay sees about 26.0 inches of precipitation a year, with negligible snowfall. The frost-free season averages 314 days, which directly shapes the planting calendar and growing potential for the area, with the last spring freeze near February 6 and the first fall freeze near December 17. On the energy side, 3,701 heating degree days and 12 cooling degree days tell the story of how often furnaces and air conditioners run during a normal year.

On PlainClimate's composite comfort index, Half Moon Bay scores 80/100 (Excellent), a blended measure that weighs temperature mildness, precipitation moderation, and extreme-weather frequency against one another. The monthly tables above turn that into a planning tool: expect the mildest highs and lows in the shoulder seasons, August-driven heat at the peak of summer, and December-driven cold at the depth of winter. Every number here is a thirty-year average, not a forecast, so any given year can and does run warmer, cooler, wetter, or drier than the normal.