Portola, CA Climate

Climate Insight: Portola, CA

In Portola, California, the NOAA 1991–2020 climate normals put the annual average temperature at 47°F, ranging from a mean daily high of 63°F to a mean daily low of 31°F. July is typically the warmest month of the year, while December is the coldest. As thirty-year averages computed from station USC00047085, these numbers smooth out year-to-year noise into a working baseline for a typical month.

Portola averages 23.3 inches of precipitation a year, with 37.8 inches typically falling as snow, and that matters as much to daily life here as temperature does. The frost-free season averages 91 days, which directly shapes the planting calendar and growing potential for the area, with the last spring freeze near June 11 and the first fall freeze near September 10. As for energy demand, 6,782 heating degree days and 144 cooling degree days tell the story of how often furnaces and air conditioners run during a normal year.

On PlainClimate's composite comfort index, Portola scores 59/100 (Moderate), a blended measure that weighs temperature mildness, precipitation moderation, and extreme-weather frequency against one another. The monthly tables above are the practical planning tool: mild highs and lows land in the shoulder seasons, July-driven heat peaks in summer, and December-driven cold sets in over deep winter. These are thirty-year averages, not a forecast - any single year can run warmer, wetter, drier, or cooler than the normal.