# Climate Design Data Workflow for Portland, OR

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

- Canonical: https://harth.build/resources/climate-data/climate-design-data-workflow-portland-or/
- Last updated: 2026-08-31
- Data source: Licensed ASHRAE Climatic Design Information / Standard 169 station data plus the locally adopted energy code. Coordinates 45.5152° 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=-122.6784&latitude=45.5152&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 | 10.4 °C (2 m gridded climatology; not a design percentile) |
| Highest monthly maximum | 40.6 °C (July) (monthly climatological statistic) |
| Lowest monthly minimum | -13.4 °C (January) (monthly climatological statistic) |
| Annual relative humidity | 81.4% (2 m gridded climatology) |
| Annual corrected precipitation | 4.07 mm/day (climatological daily rate) |
| Annual wind speed | 2.33 m/s (10 m gridded climatology; not a structural design wind speed) |

## Direct answer

NASA POWER's 2001–2020 climatology at the Portland, OR reference point reports an annual mean 2 m temperature of 10.4 °C and relative humidity of 81.4%. The highest monthly maximum is 40.6 °C in July, while the lowest monthly minimum is -13.4 °C in January; 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 4.07 mm/day and annual 10 m wind speed is 2.33 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 |

## Portland, OR 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 | 3.55 | 16.68 | -13.41 | 91.84 | 6.97 | 2.90 |
| February | 4.13 | 18.83 | -9.60 | 88.64 | 5.09 | 2.61 |
| March | 6.30 | 23.45 | -5.38 | 87.09 | 5.74 | 2.52 |
| April | 8.52 | 28.66 | -2.68 | 84.16 | 3.98 | 2.25 |
| May | 12.22 | 33.87 | 0.47 | 82.06 | 2.56 | 2.00 |
| June | 14.92 | 37.84 | 4.04 | 79.60 | 1.83 | 1.99 |
| July | 18.92 | 40.56 | 7.04 | 70.30 | 0.35 | 1.93 |
| August | 19.73 | 40.12 | 6.61 | 64.72 | 0.63 | 1.92 |
| September | 16.50 | 38.54 | 2.13 | 68.31 | 1.90 | 2.00 |
| October | 10.93 | 30.67 | -4.22 | 79.76 | 4.43 | 2.28 |
| November | 6.14 | 19.33 | -9.38 | 88.95 | 7.24 | 2.73 |
| December | 3.06 | 15.88 | -12.52 | 92.08 | 8.10 | 2.85 |

![Monthly mean, maximum and minimum air temperature for Climate Design Data Workflow for Portland, OR](https://efwwel0vyt9vy5so.public.blob.vercel-storage.com/images/climate-data/climate-design-data-workflow-portland-or/chart-temperature-1344.webp)

*Monthly air temperature for Climate Design Data Workflow for Portland, OR, plotted from the table above.*

![Mean daily precipitation by month for Climate Design Data Workflow for Portland, OR](https://efwwel0vyt9vy5so.public.blob.vercel-storage.com/images/climate-data/climate-design-data-workflow-portland-or/chart-precipitation-1344.webp)

*Mean daily precipitation for Climate Design Data Workflow for Portland, OR, plotted from the table above.*

## Month-by-month climate interpretation

- **January:** mean temperature 3.55 °C is 6.89 °C below the annual mean; the monthly max–min span is 30.09 °C. Relative humidity is 91.84% (10.42 points above annual), while corrected precipitation at 6.97 mm/day is 2.90 mm/day wetter than the annual daily rate.
- **February:** mean temperature 4.13 °C is 6.31 °C below the annual mean; the monthly max–min span is 28.43 °C. Relative humidity is 88.64% (7.22 points above annual), while corrected precipitation at 5.09 mm/day is 1.02 mm/day wetter than the annual daily rate.
- **March:** mean temperature 6.30 °C is 4.14 °C below the annual mean; the monthly max–min span is 28.83 °C. Relative humidity is 87.09% (5.67 points above annual), while corrected precipitation at 5.74 mm/day is 1.67 mm/day wetter than the annual daily rate.
- **April:** mean temperature 8.52 °C is 1.92 °C below the annual mean; the monthly max–min span is 31.34 °C. Relative humidity is 84.16% (2.74 points above annual), while corrected precipitation at 3.98 mm/day is 0.09 mm/day drier than the annual daily rate.
- **May:** mean temperature 12.22 °C is 1.78 °C above the annual mean; the monthly max–min span is 33.40 °C. Relative humidity is 82.06% (0.64 points above annual), while corrected precipitation at 2.56 mm/day is 1.51 mm/day drier than the annual daily rate.
- **June:** mean temperature 14.92 °C is 4.48 °C above the annual mean; the monthly max–min span is 33.80 °C. Relative humidity is 79.60% (1.82 points below annual), while corrected precipitation at 1.83 mm/day is 2.24 mm/day drier than the annual daily rate.
- **July:** mean temperature 18.92 °C is 8.48 °C above the annual mean; the monthly max–min span is 33.52 °C. Relative humidity is 70.30% (11.12 points below annual), while corrected precipitation at 0.35 mm/day is 3.72 mm/day drier than the annual daily rate.
- **August:** mean temperature 19.73 °C is 9.29 °C above the annual mean; the monthly max–min span is 33.51 °C. Relative humidity is 64.72% (16.70 points below annual), while corrected precipitation at 0.63 mm/day is 3.44 mm/day drier than the annual daily rate.
- **September:** mean temperature 16.50 °C is 6.06 °C above the annual mean; the monthly max–min span is 36.41 °C. Relative humidity is 68.31% (13.11 points below annual), while corrected precipitation at 1.90 mm/day is 2.17 mm/day drier than the annual daily rate.
- **October:** mean temperature 10.93 °C is 0.49 °C above the annual mean; the monthly max–min span is 34.89 °C. Relative humidity is 79.76% (1.66 points below annual), while corrected precipitation at 4.43 mm/day is 0.36 mm/day wetter than the annual daily rate.
- **November:** mean temperature 6.14 °C is 4.30 °C below the annual mean; the monthly max–min span is 28.71 °C. Relative humidity is 88.95% (7.53 points above annual), while corrected precipitation at 7.24 mm/day is 3.17 mm/day wetter than the annual daily rate.
- **December:** mean temperature 3.06 °C is 7.38 °C below the annual mean; the monthly max–min span is 28.40 °C. Relative humidity is 92.08% (10.66 points above annual), while corrected precipitation at 8.10 mm/day is 4.03 mm/day wetter than the annual daily rate.

Harth retrieved this point climatology from NASA POWER API v2.9.7 for location record us:portland-or. 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 Seattle, WA](https://harth.build/resources/climate-data/climate-design-data-workflow-seattle-wa.md)
- [Climate Design Data Workflow for Boise, ID](https://harth.build/resources/climate-data/climate-design-data-workflow-boise-id.md)
- [Sun Path & Solar Angles for Portland, OR](https://harth.build/resources/solar-data/sun-path-and-solar-angles-portland-or.md)

## Sources and method

Licensed ASHRAE Climatic Design Information / Standard 169 station data plus the locally adopted energy code. Coordinates 45.5152° 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=-122.6784&latitude=45.5152&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=-122.6784&latitude=45.5152&format=JSON)

## Frequently asked questions

### What does NASA POWER climatology show for Portland, OR?

For the Portland, OR reference point, the 2001–2020 NASA POWER climatology reports 10.4 °C annual mean temperature, 81.4% relative humidity and 4.07 mm/day corrected precipitation. The monthly maximum peaks at 40.6 °C in July.

### Can the Portland, OR climatology replace project design temperatures or an hourly weather file?

No. The Portland, OR response is gridded monthly climatology; its lowest monthly minimum of -13.4 °C in January 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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