Written and maintained by CASRAI Editorial Board
Last updated
NOAA Atlas 14 is the federal precipitation frequency standard for the United States, published by the National Oceanic and Atmospheric Administration (NOAA) National Weather Service (NWS) Hydrometeorological Design Studies Center (HDSC). It delivers localized point precipitation frequency estimates, depth-duration-frequency (DDF) curves, intensity-duration-frequency (IDF) curves, and spatial ASCII raster grids used in civil engineering, stormwater management, flood hazard modeling, and hydrological research.
What it is
NOAA Atlas 14, titled Precipitation-Frequency Atlas of the United States, provides statistical recurrence estimates for heavy rainfall across durations from 5 minutes to 60 days and average recurrence intervals (ARIs) from 1 to 1,000 years. These estimates serve as the hydrological baseline for sizing culverts, detention basins, urban storm sewers, bridges, and spillways across federal, state, and local jurisdictions.
The atlas replaced historical U.S. Weather Bureau standards, including Technical Paper No. 40 (TP-40, 1961), NOAA Atlas 2 (1973), and NWS Hydro-35 (1977). NOAA Atlas 14 applies regional frequency analysis based on L-moments to fit generalized extreme value (GEV) distributions across dense gauge networks. This framework minimizes sampling error and yields quantifiable 90% confidence intervals around each estimate.
Users access the dataset via the web-based Precipitation Frequency Data Server (PFDS). The repository aligns with federal open data guidelines, offering unrestricted public access for research, engineering design, and environmental assessments without licensing fees.
Who runs it and what it covers
NOAA Atlas 14 is developed and maintained by the Hydrometeorological Design Studies Center (HDSC) within the Office of Water Prediction (OWP) of NOAA’s National Weather Service in Silver Spring, Maryland. Funded incrementally through regional and state consortiums, the atlas was published in discrete volumes:
- Volumes 1–3: Southwest, Ohio Basin & Islands: AZ, NV, NM, UT, SE CA; DE, DC, IL, IN, KY, MD, NJ, NC, OH, PA, SC, TN, VA, WV; PR and USVI (Bonnin et al., 2006).
- Volumes 4–7: Pacific, California & Alaska: Hawaii and Pacific territories; California; Alaska (Perica et al., 2011).
- Volumes 8–11: Midwest, Southeast, Northeast & Texas: 23 central and eastern states plus Texas (Perica et al., 2013–2018).
- Volume 12: Interior Northwest: Idaho, Montana, Wyoming.
Oregon and Washington were never finalized under Atlas 14, requiring engineers there to use older regional literature. The repository follows FAIR data principles, ensuring interoperability alongside repositories like the USGS ScienceBase research repository.
How to search or use it
Extracting estimates and spatial rasters through the Precipitation Frequency Data Server (PFDS) follows a standardized seven-step workflow:
- Access the PFDS portal: Open the NOAA HDSC Precipitation Frequency Data Server. Select a state or territory from the drop-down menu or map to launch the regional application.
- Define the location: Enter coordinates in decimal degrees (latitude and longitude, using negative signs for west and south), select a station from the directory, or enter an address. Alternatively, click the interactive map crosshairs over your target basin.
- Set data options: Configure parameters in the top panel:
- Data type: Select Precipitation depth (accumulated inches or mm) or Precipitation intensity (rate per hour).
- Units: Choose English (inches, in/hr) or Metric (mm, mm/hr).
- Time series type: Choose Partial duration series (PDS) (standard for storm design under a 10-year return period) or Annual maximum series (AMS).
- Review tabular estimates: Click the PF tabular tab to inspect estimates from 5 minutes to 60 days across return periods from 1 to 1,000 years. Each cell displays the expected value and 90% confidence limits.
- Inspect frequency graphs: Click the PF graphical tab to view and export Depth-Duration-Frequency (DDF) or Intensity-Duration-Frequency (IDF) curves for hydraulic modeling software like HEC-HMS.
- Obtain supplementary distributions: Use the Supplementary information tab to download rainfall temporal distributions by quartile, regional seasonality graphs, or historical annual maximum series records.
- Download GIS grids: For distributed watershed analysis, open the PFDS GIS Grids page. Download zipped ESRI ASCII raster grids and companion XML metadata files detailing projections, resolution, and units.
Strengths and limits
Strengths
- Regional frequency analysis: Uses pooled L-moments across gauge networks to dampen single-station anomalies.
- 90% confidence intervals: Every estimate provides 5% and 95% confidence bounds for engineering risk analysis.
- Broad temporal scope: Covers 5-minute convective bursts up to 60-day storms for diverse watershed scales.
- Open access: Public domain distribution without logins supports reproducible research, comparable to platforms like Zenodo.
Limits
- Stationarity assumption: Atlas 14 assumes extreme precipitation frequencies remain statistically invariant over time. Historical averages may underestimate storm frequencies in changing climates.
- Boundary discrepancies: Because volumes were published across different years with varying record lengths, minor step-discontinuities occur across state lines.
- Geographic omissions: Oregon and Washington lack Atlas 14 volumes, requiring older engineering references.
The transition to NOAA Atlas 15
To address stationarity and spatial fragmentation, NOAA’s Office of Water Prediction is developing NOAA Atlas 15, funded under the Bipartisan Infrastructure Law (BIL):
- Unified national domain: Covers the contiguous United States (CONUS) and external territories in a continuous grid.
- Historical nonstationary analysis (Volume 1): Incorporates observed multi-decadal trends in rainfall records.
- Future climate projections (Volume 2): Uses downscaled CMIP6 model projections through 2100 across varied emission scenarios.
Following a Montana pilot, preliminary CONUS data is scheduled for release in late 2026, with publication in 2027. Until federal agencies and municipal stormwater manuals formally incorporate Atlas 15, NOAA Atlas 14 remains the binding legal standard for hydraulic design.
Alternatives
| Dataset / Platform | Custodian | Coverage | Statistical Basis | Primary Use Case |
|---|---|---|---|---|
| NOAA Atlas 14 | NOAA NWS / HDSC | U.S. States & Territories (except Pacific NW) | Stationary (L-moments / GEV) | Binding regulatory baseline for civil drainage and FEMA flood studies. |
| NOAA Atlas 15 | NOAA NWS / OWP | Nationwide (CONUS & oCONUS) | Nonstationary (Trends & CMIP6 projections to 2100) | Upcoming national standard for climate-resilient infrastructure. |
| U.S. Weather Bureau TP-40 | U.S. Weather Bureau (1961) | Contiguous U.S. | Stationary (Isopluvial paper maps) | Legacy baseline, superseded by Atlas 14 but cited in older local codes. |
| NRCS NEH-4 / TR-55 | USDA NRCS | United States | Stationary (Synthetic design storms: Type I, IA, II, III) | Runoff hydrograph generation in agricultural and small watershed modeling. |
| Cornell NRCC Extreme Precipitation | Northeast Regional Climate Center | Northeast U.S. | Stationary & gridded interpolation | Regional supplement for New York and New England infrastructure agencies. |
FAQ
What is the difference between partial duration series (PDS) and annual maximum series (AMS) in NOAA Atlas 14?
An Annual Maximum Series (AMS) captures only the single largest event in each calendar or water year at a gauge. A Partial Duration Series (PDS) includes all discrete events exceeding a defined threshold, even if several occur in one year. For return periods of 10 years or greater, AMS and PDS results converge. For frequent storms (1 to 5 years), PDS yields slightly higher rainfall depths, better representing stormwater design conditions. NOAA Atlas 14 applies Langbein empirical factors to convert between series.
How should researchers cite NOAA Atlas 14 in academic publications?
Citations should specify the regional volume number, version, and lead authors. For example, Volume 2 in APA style: Bonnin, G. M., Martin, D., Lin, B., Parzybok, T., Yekta, M., & Riley, D. (2006). Precipitation-Frequency Atlas of the United States, NOAA Atlas 14, Volume 2, Version 3.0: Ohio River Basin and Surrounding States. Silver Spring, MD: NOAA, National Weather Service. Volumes 4 through 11 cite Sanja Perica as lead author with the volume number and year.
Why are there differences at state or regional volume boundaries in NOAA Atlas 14?
Because the twelve volumes were produced sequentially over more than a decade with distinct regional funding, each volume analyzed differing gauge observation periods. These chronological differences created minor edge discrepancies at project boundaries, most evident at rare return intervals (such as 100-year events). Hydrologists near state borders should examine both adjacent volumes and consult local drainage manuals.
When will NOAA Atlas 15 replace NOAA Atlas 14?
NOAA Atlas 15 is actively in development. Contiguous U.S. (CONUS) data is scheduled for peer review in late 2026, followed by publication in 2027. Outside CONUS volumes will follow. Until municipal stormwater regulations and federal guidelines formally mandate Atlas 15, NOAA Atlas 14 remains the legally enforceable design standard.
Does NOAA Atlas 14 require an account or subscription fee?
No. NOAA Atlas 14 tables, charts, and GIS raster grids on the Precipitation Frequency Data Server (PFDS) are public domain federal assets. Data can be viewed and downloaded freely without user accounts, subscriptions, or API tokens.
Sources
- NOAA National Weather Service Hydrometeorological Design Studies Center. (2026). Precipitation Frequency Data Server (PFDS). https://hdsc.nws.noaa.gov/pfds/ (read 2026-11-07).
- NOAA HDSC. (2026). NOAA Atlas 14 Precipitation Frequency Estimates in GIS Compatible Format. https://hdsc.nws.noaa.gov/pfds/pfds_gis.html (read 2026-11-07).
- NOAA HDSC. (2026). Point Precipitation Frequency Estimates Interface: Contiguous United States. https://hdsc.nws.noaa.gov/pfds/pfds_map_cont.html (read 2026-11-07).
- NOAA NWS Office of Water Prediction. (2026). Documentation of the Precipitation Frequency Data Server (Section 5). https://www.weather.gov/media/owp/hdsc_documents/NA14_Sec5_PFDS.pdf (read 2026-11-07).
- NOAA National Weather Service Office of Water Prediction. (2026). NOAA Atlas 15 Development and Progress Reports. https://www.weather.gov/owp/hdsc_pfds (read 2026-11-07).
