# Climate Design Data Workflow for San Francisco, CA

> A source-first workflow for retrieving and recording building-design climate conditions for San Francisco, CA without mixing climate normals, code zones, and HVAC design percentiles.

- Canonical: https://harth.build/resources/climate-data/climate-design-data-workflow-san-francisco-ca/
- Last updated: 2026-08-31
- Data source: 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](https://power.larc.nasa.gov/docs/services/api/temporal/climatology/) and [exact point response](https://power.larc.nasa.gov/api/temporal/climatology/point?parameters=T2M%2CT2M_MAX%2CT2M_MIN%2CRH2M%2CPRECTOTCORR%2CWS10M&community=SB&longitude=-122.4194&latitude=37.7749&format=JSON), 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.

## Key facts

| Fact | Value |
| --- | --- |
| NASA POWER climatology | 20-year Meteorological and Solar Monthly & Annual Climatologies (January 2001 - December 2020) (API v2.9.7; LST) |
| Annual mean temperature | 13.6 °C (2 m gridded climatology; not a design percentile) |
| Highest monthly maximum | 39.0 °C (September) (monthly climatological statistic) |
| Lowest monthly minimum | -0.8 °C (December) (monthly climatological statistic) |
| Annual relative humidity | 77.0% (2 m gridded climatology) |
| Annual corrected precipitation | 1.60 mm/day (climatological daily rate) |
| Annual wind speed | 3.49 m/s (10 m gridded climatology; not a structural design wind speed) |

## 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](https://www.linkedin.com/company/harth-build) · 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.

| Field | Required record |
| --- | --- |
| Station | Name, ID, coordinates and elevation |
| Source | Publisher, edition and licensed/public status |
| Heating | 99.6% and 99% dry-bulb |
| Cooling | 0.4%, 1% and 2% dry-bulb plus coincident wet-bulb |
| Moisture | Dew-point or humidity design condition used |
| Code | Adopted edition, amendments and effective date |

## San Francisco, CA NASA POWER monthly climate screening table

| Month | Mean °C | Monthly max °C | Monthly min °C | RH % | Precipitation mm/day | Wind at 10 m m/s |
| --- | ---: | ---: | ---: | ---: | ---: | ---: |
| January | 9.35 | 21.04 | -0.74 | 84.09 | 3.23 | 3.26 |
| February | 10.29 | 22.20 | 1.06 | 82.12 | 3.62 | 3.51 |
| March | 11.43 | 24.67 | 1.32 | 81.77 | 2.66 | 3.52 |
| April | 12.23 | 29.61 | 3.10 | 79.65 | 1.39 | 3.76 |
| May | 13.96 | 33.66 | 4.98 | 77.70 | 0.59 | 3.93 |
| June | 15.98 | 34.29 | 7.55 | 73.62 | 0.20 | 3.97 |
| July | 16.81 | 33.42 | 9.47 | 74.28 | 0.04 | 3.69 |
| August | 17.33 | 35.46 | 9.86 | 74.12 | 0.04 | 3.53 |
| September | 17.58 | 39.03 | 9.32 | 69.74 | 0.12 | 3.25 |
| October | 15.85 | 34.30 | 5.77 | 69.13 | 0.95 | 3.01 |
| November | 12.36 | 27.70 | 0.72 | 76.00 | 2.06 | 3.03 |
| December | 9.62 | 20.15 | -0.79 | 81.89 | 4.46 | 3.45 |

![Monthly mean, maximum and minimum air temperature for Climate Design Data Workflow for San Francisco, CA](https://efwwel0vyt9vy5so.public.blob.vercel-storage.com/images/climate-data/climate-design-data-workflow-san-francisco-ca/chart-temperature-1344.webp)

*Monthly air temperature for Climate Design Data Workflow for San Francisco, CA, plotted from the table above.*

![Mean daily precipitation by month for Climate Design Data Workflow for San Francisco, CA](https://efwwel0vyt9vy5so.public.blob.vercel-storage.com/images/climate-data/climate-design-data-workflow-san-francisco-ca/chart-precipitation-1344.webp)

*Mean daily precipitation for Climate Design Data Workflow for San Francisco, CA, plotted from the table above.*

## 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](https://harth.build/resources/climate-data.md)
- [ASHRAE / IECC Climate Zones Explained (Zones 1–8, A/B/C)](https://harth.build/resources/climate-data/ashrae-climate-zones-explained.md)
- [Heating & Cooling Design Temperatures (99%, 1% / 0.4%)](https://harth.build/resources/climate-data/heating-and-cooling-design-temperatures.md)
- [Climate Design Data Workflow for Los Angeles, CA](https://harth.build/resources/climate-data/climate-design-data-workflow-los-angeles-ca.md)
- [Climate Design Data Workflow for San Diego, CA](https://harth.build/resources/climate-data/climate-design-data-workflow-san-diego-ca.md)
- [Sun Path & Solar Angles for San Francisco, CA](https://harth.build/resources/solar-data/sun-path-and-solar-angles-san-francisco-ca.md)

## 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](https://power.larc.nasa.gov/docs/services/api/temporal/climatology/) and [exact point response](https://power.larc.nasa.gov/api/temporal/climatology/point?parameters=T2M%2CT2M_MAX%2CT2M_MIN%2CRH2M%2CPRECTOTCORR%2CWS10M&community=SB&longitude=-122.4194&latitude=37.7749&format=JSON), 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](https://power.larc.nasa.gov/docs/services/api/temporal/climatology/)

- [power.larc.nasa.gov](https://power.larc.nasa.gov/api/temporal/climatology/point?parameters=T2M%2CT2M_MAX%2CT2M_MIN%2CRH2M%2CPRECTOTCORR%2CWS10M&community=SB&longitude=-122.4194&latitude=37.7749&format=JSON)

## Frequently asked questions

### What does NASA POWER climatology show for San Francisco, CA?

For the San Francisco, CA reference point, the 2001–2020 NASA POWER climatology reports 13.6 °C annual mean temperature, 77.0% relative humidity and 1.60 mm/day corrected precipitation. The monthly maximum peaks at 39.0 °C in September.

### Can the San Francisco, CA climatology replace project design temperatures or an hourly weather file?

No. The San Francisco, CA response is gridded monthly climatology; its lowest monthly minimum of -0.8 °C in December is not a code percentile or observed site extreme. Verify elevation, local exposure, the required weather file or design-condition source and the current adopted code.

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