Climate Design Data Workflow for San Francisco, CA

Direct answer

NASA POWER's 2001–2020 climatology at the San Francisco, CA reference point reports an annual mean 2 m temperature of 13.6 °C and relative humidity of 77.0%. The highest monthly maximum is 39.0 °C in September, while the lowest monthly minimum is -0.8 °C in December; these are screening statistics, not code design temperatures. The point response uses LST and the 20-year Meteorological and Solar Monthly & Annual Climatologies (January 2001 - December 2020); its annual corrected precipitation is 1.60 mm/day and annual 10 m wind speed is 3.49 m/s. Use the monthly series to screen source selection before applying project design conditions. NASA POWER is gridded climatology: verify elevation, microclimate, urban exposure, station or weather-file suitability, current code edition and the authority's required source before design use.

Content and cited inputs reviewed by Harth team · Published 2026-08-17 · Updated 2026-08-31.

Which climate inputs control the design?

1. Confirm the project jurisdiction and adopted energy-code edition.
2. Select the authoritative station and record why it applies.
3. Record heating dry-bulb percentiles and cooling dry-bulb with coincident moisture conditions.
4. Keep IP/SI units, edition, observation period and retrieval date with every value.
5. Separate climate-zone envelope requirements from HVAC sizing conditions.

San Francisco, CA NASA POWER monthly climate screening table

Month-by-month climate interpretation

• January: mean temperature 9.35 °C is 4.23 °C below the annual mean; the monthly max–min span is 21.78 °C. Relative humidity is 84.09% (7.10 points above annual), while corrected precipitation at 3.23 mm/day is 1.63 mm/day wetter than the annual daily rate.
• February: mean temperature 10.29 °C is 3.29 °C below the annual mean; the monthly max–min span is 21.14 °C. Relative humidity is 82.12% (5.13 points above annual), while corrected precipitation at 3.62 mm/day is 2.02 mm/day wetter than the annual daily rate.
• March: mean temperature 11.43 °C is 2.15 °C below the annual mean; the monthly max–min span is 23.35 °C. Relative humidity is 81.77% (4.78 points above annual), while corrected precipitation at 2.66 mm/day is 1.06 mm/day wetter than the annual daily rate.
• April: mean temperature 12.23 °C is 1.35 °C below the annual mean; the monthly max–min span is 26.51 °C. Relative humidity is 79.65% (2.66 points above annual), while corrected precipitation at 1.39 mm/day is 0.21 mm/day drier than the annual daily rate.
• May: mean temperature 13.96 °C is 0.38 °C above the annual mean; the monthly max–min span is 28.68 °C. Relative humidity is 77.70% (0.71 points above annual), while corrected precipitation at 0.59 mm/day is 1.01 mm/day drier than the annual daily rate.
• June: mean temperature 15.98 °C is 2.40 °C above the annual mean; the monthly max–min span is 26.74 °C. Relative humidity is 73.62% (3.37 points below annual), while corrected precipitation at 0.20 mm/day is 1.40 mm/day drier than the annual daily rate.
• July: mean temperature 16.81 °C is 3.23 °C above the annual mean; the monthly max–min span is 23.95 °C. Relative humidity is 74.28% (2.71 points below annual), while corrected precipitation at 0.04 mm/day is 1.56 mm/day drier than the annual daily rate.
• August: mean temperature 17.33 °C is 3.75 °C above the annual mean; the monthly max–min span is 25.60 °C. Relative humidity is 74.12% (2.87 points below annual), while corrected precipitation at 0.04 mm/day is 1.56 mm/day drier than the annual daily rate.
• September: mean temperature 17.58 °C is 4.00 °C above the annual mean; the monthly max–min span is 29.71 °C. Relative humidity is 69.74% (7.25 points below annual), while corrected precipitation at 0.12 mm/day is 1.48 mm/day drier than the annual daily rate.
• October: mean temperature 15.85 °C is 2.27 °C above the annual mean; the monthly max–min span is 28.53 °C. Relative humidity is 69.13% (7.86 points below annual), while corrected precipitation at 0.95 mm/day is 0.65 mm/day drier than the annual daily rate.
• November: mean temperature 12.36 °C is 1.22 °C below the annual mean; the monthly max–min span is 26.98 °C. Relative humidity is 76.00% (0.99 points below annual), while corrected precipitation at 2.06 mm/day is 0.46 mm/day wetter than the annual daily rate.
• December: mean temperature 9.62 °C is 3.96 °C below the annual mean; the monthly max–min span is 20.94 °C. Relative humidity is 81.89% (4.90 points above annual), while corrected precipitation at 4.46 mm/day is 2.86 mm/day wetter than the annual daily rate.

Harth retrieved this point climatology from NASA POWER API v2.9.7 for location record us:san-francisco-ca. It is a reproducible screening dataset, not an hourly weather file, forecast, code design condition or substitute for local professional review.

Where can you explore related guidance?

• Explore all climate data guidance
• ASHRAE / IECC Climate Zones Explained (Zones 1–8, A/B/C)
• Heating & Cooling Design Temperatures (99%, 1% / 0.4%)
• Climate Design Data Workflow for Los Angeles, CA
• Climate Design Data Workflow for San Diego, CA
• Sun Path & Solar Angles for San Francisco, CA

Sources and method

Licensed ASHRAE Climatic Design Information / Standard 169 station data plus the locally adopted energy code. Coordinates 37.7749° N (America/Los_Angeles) are approximate routing references. Figures are illustrative — confirm the representative station and current edition. Climate screening data from the NASA POWER Climatology API documentation and exact point response, retrieved 2026-08-31; source period: 20-year Meteorological and Solar Monthly & Annual Climatologies (January 2001 - December 2020). NASA POWER values are gridded screening statistics, not code design conditions or guaranteed local observations.

Source links

• power.larc.nasa.gov

• power.larc.nasa.gov