The Severe Weather Data Inventory (SWDI) is an integrated database of severe weather records for the United States. SWDI enables a user to search through a variety of source data sets in the NCDC (now NCEI) archive in order to find records covering a particular time period and geographic region, and then to download the results of the search in a variety of formats. The formats currently supported are Shapefile (for GIS), KMZ (for Google Earth), CSV (comma-separated), and XML. The current data layers in SWDI are: Storm Cells from NEXRAD (Level-III Storm Structure Product); Hail Signatures from NEXRAD (Level-III Hail Product); Mesocyclone Signatures from NEXRAD (Level-III Meso Product); Digital Mesocyclone Detection Algorithm from NEXRAD (Level-III MDA Product); Tornado Signature from NEXRAD (Level-III TVS Product); Preliminary Local Storm Reports from the NOAA National Weather Service; Lightning Strikes from Vaisala NLDN.

Global Surface Summary of the Day is derived from The Integrated Surface Hourly (ISH) dataset. The ISH dataset includes global data obtained from the USAF Climatology Center, located in the Federal Climate Complex with NCDC. The latest daily summary data are normally available 1-2 days after the date-time of the observations used in the daily summaries. The online data files begin with 1929 and are at the time of this writing at the Version 8 software level. Over 9000 stations' data are typically available. The daily elements included in the dataset (as available from each station) are: Mean temperature (.1 Fahrenheit) Mean dew point (.1 Fahrenheit) Mean sea level pressure (.1 mb) Mean station pressure (.1 mb) Mean visibility (.1 miles) Mean wind speed (.1 knots) Maximum sustained wind speed (.1 knots) Maximum wind gust (.1 knots) Maximum temperature (.1 Fahrenheit) Minimum temperature (.1 Fahrenheit) Precipitation amount (.01 inches) Snow depth (.1 inches) Indicator for occurrence of: Fog, Rain or Drizzle, Snow or Ice Pellets, Hail, Thunder, Tornado/Funnel Cloud Global summary of day data for 18 surface meteorological elements are derived from the synoptic/hourly observations contained in USAF DATSAV3 Surface data and Federal Climate Complex Integrated Surface Hourly (ISH). Historical data are generally available for 1929 to the present, with data from 1973 to the present being the most complete. For some periods, one or more countries' data may not be available due to data restrictions or communications problems. In deriving the summary of day data, a minimum of 4 observations for the day must be present (allows for stations which report 4 synoptic observations/day). Since the data are converted to constant units (e.g, knots), slight rounding error from the originally reported values may occur (e.g, 9.9 instead of 10.0). The mean daily values described below are based on the hours of operation for the station. For some stations/countries, the visibility will sometimes 'cluster' around a value (such as 10 miles) due to the practice of not reporting visibilities greater than certain distances. The daily extremes and totals--maximum wind gust, precipitation amount, and snow depth--will only appear if the station reports the data sufficiently to provide a valid value. Therefore, these three elements will appear less frequently than other values. Also, these elements are derived from the stations' reports during the day, and may comprise a 24-hour period which includes a portion of the previous day. The data are reported and summarized based on Greenwich Mean Time (GMT, 0000Z - 2359Z) since the original synoptic/hourly data are reported and based on GMT.

These daily weather records were compiled from a subset of stations in the Global Historical Climatological Network (GHCN)-Daily dataset. A weather record is considered broken if the value exceeds the maximum (or minimum) value recorded for an eligible station. A weather record is considered tied if the value is the same as the maximum (or minimum) value recorded for an eligible station. Daily weather parameters include Highest Min/Max Temperature, Lowest Min/Max Temperature, Highest Precipitation, Highest Snowfall and Highest Snow Depth. All stations meet defined eligibility criteria. For this application, a station is defined as the complete daily weather records at a particular location, having a unique identifier in the GHCN-Daily dataset. For a station to be considered for any weather parameter, it must have a minimum of 30 years of data with more than 182 days complete in each year. This is effectively a 30-year record of service requirement, but allows for inclusion of some stations which routinely shut down during certain seasons. Small station moves, such as a move from one property to an adjacent property, may occur within a station history. However, larger moves, such as a station moving from downtown to the city airport, generally result in the commissioning of a new station identifier. This tool treats each of these histories as a different station. In this way, it does not thread the separate histories into one record for a city. Records Timescales are characterized in three ways. In order of increasing noteworthiness, they are Daily Records, Monthly Records and All Time Records. For a given station, Daily Records refers to the specific calendar day: (e.g., the value recorded on March 7th compared to every other March 7th). Monthly Records exceed all values observed within the specified month (e.g., the value recorded on March 7th compared to all values recorded in every March). All-Time Records exceed the record of all observations, for any date, in a station's period of record. The Date Range and Location features are used to define the time and location ranges which are of interest to the user. For example, selecting a date range of March 1, 2012 through March 15, 2012 will return a list of records broken or tied on those 15 days. The Location Category and Country menus allow the user to define the geographic extent of the records of interest. For example, selecting Oklahoma will narrow the returned list of records to those that occurred in the state of Oklahoma, USA. The number of records broken for several recent periods is summarized in the table and updated daily. Due to late-arriving data, the number of recent records is likely underrepresented in all categories, but the ratio of records (warm to cold, for example) should be a fairly strong estimate of a final outcome. There are many more precipitation stations than temperature stations, so the raw number of precipitation records will likely exceed the number of temperature records in most climatic situations.

In March 2015, data for thirteen Alaskan climate divisions were added to the NClimDiv data set. Data for the new Alaskan climate divisions begin in 1925 through the present and are included in all monthly updates. Alaskan climate data include the following elements for divisional and statewide coverage: average temperature, maximum temperature (highs), minimum temperature (lows), and precipitation. The Alaska NClimDiv data were created and updated using similar methodology as that for the CONUS, but with a different approach to establishing the underlying climatology. The Alaska data are built upon the 1971-2000 PRISM averages whereas the CONUS values utilize a base climatology derived from the NClimGrid data set. In January 2025, the National Centers for Environmental Information (NCEI) began summarizing the State of the Climate for Hawaii. This was made possible through a collaboration between NCEI and the University of Hawaii/Hawaii Climate Data Portal and completes a long-standing gap in NCEI's ability to characterize the State of the Climate for all 50 states. NCEI maintains monthly statewide, divisional, and gridded average temperature, maximum temperatures (highs), minimum temperature (lows) and precipitation data for Hawaii over the period 1991-2025. As of November 2018, NClimDiv includes county data and additional inventory files In March 2015, data for thirteen Alaskan climate divisions were added to the NClimDiv data set. Data for the new Alaskan climate divisions begin in 1925 through the present and are included in all monthly updates. Alaskan climate data include the following elements for divisional and statewide coverage: average temperature, maximum temperature (highs), minimum temperature (lows), and precipitation. The Alaska NClimDiv data were created and updated using similar methodology as that for the CONUS, but with a different approach to establishing the underlying climatology. The Alaska data are built upon the 1971-2000 PRISM averages whereas the CONUS values utilize a base climatology derived from the NClimGrid data set.

As of November 2018, NClimDiv includes county data and additional inventory files.

The NOAA Weather and Climate Toolkit is an application that provides simple visualization and data export of weather and climatological data archived at NCDC. The Toolkit also provides access to weather and climate web services provided from NCDC and other organizations. The Viewer provides tools for displaying custom data overlay, Web Map Services (WMS), animations and basic filters. The export of images and movies is provided in multiple formats. The Data Exporter allows for data export in both vector point/line/polygon and raster grid formats. Current data types supported include: CF-compliant Fridded NetCDF; Generic CF-compliant Irregularly-Spaced/Curvilinear Gridded NetCDF/HDF; GRIB1, GRIB2, GINI, GEMPAK, HDF(CF-compliant) and more gridded formats; GPES Satellite AREA Files; NEXRAD Radar Data(Level-II and Level-III); U.S. Drought Monitor Service from the National Drought Mitigation Center (NDMC); OPeNDAP support for Gridded Datasets

The dataset consists of hourly U.S. surface airways observations (SAO). These observations extend as far back as 1928, from the time when commercial aviation began in the United States and meteorological observing stations were established at many airports (although occasionally, early-period SAO's were taken at U.S. Weather Bureau city offices). For most stations, this dataset extends through June of 1948. The major data variables are as follows: WBAN Station Identification Number, observational type, ceiling and cloud, visibility, present weather data, temperature, wind and pressure. The observations are generally recorded for the 24-hour period midnight to midnight, although many stations did not record 24-hour observations, especially early in the period when commercial aviation was just getting started. Two output keying formats were created to adjust to an observational form change during the period. One format was generally used for years 1928-33, and the other for sets from around 1934 through June of 1948. Each keying format was designed to reflect the data as entered on the observational form for ease of keying by key entry personnel, who were not trained meteorological technicians. The "raw" observations which comprise the DSI-3851 dataset were quality checked, to include data adjustments, and converted to NCDC's Integrated Surface Hourly (ISH) format.

The complimentary data to this collection can be found in the Surface Weather Observation 1001 Forms (Keyed) collection.

Surface Weather Observation 1001 Forms is a set of historical manuscript records for the period 1893-1948. The collection includes two very similar form types: Form 1001, in use by the US Weather Bureau, and Form 1, in use by the US Army and Navy. NCDC Climate Data Modernization Program (CDMP) scanned the vast majority of these forms in order to fill in the observation gap prior to the time when commercial aviation began in the U.S. Many forms contiaining observations taken on foreign soil have not yet been scanned. Observations were recorded two to four times daily beginning as early as 1893 at city Weather Bureau Offices. During the 1930s many of these city stations gradually moved to airport locations.

Through 1936 observations were taken twice daily; then in 1937 the general practice was to record four observations per day. The data elements are as follows: station pressure, sea level pressure, dry and wet bulb temperature, dew point, maximum and minimum temperature, wind direction and speed, precipitation, cloud amount and type, ceiling, state of weather and visibility. It should be noted that not all elements are present for all stations in this dataset, and that ceiling and visibility observations did not begin at the city offices until the 1930's. Official surface weather observation standards can be found in the Circular N manuals. The vast majority of records are available online, but some records are still only available in the physical format only.

The NOAA Monthly U.S. Climate Gridded Dataset (NClimGrid) consists of four climate variables derived from the GHCN-D dataset: maximum temperature, minimum temperature, average temperature and precipitation. Each file provides monthly values in a 5x5 lat/lon grid for the Continental United States. Data is available from 1895 to the present. In March 2015, new Alaska data was included in the nClimDiv dataset. The Alaska nClimDiv data were created and updated using similar methodology as that for the CONUS. It includes maximum temperature, minimum temperature, average temperature and precipitation. In January 2025, the National Centers for Environmental Information (NCEI) began summarizing the State of the Climate for Hawaii. This was made possible through a collaboration between NCEI and the University of Hawaii/Hawaii Climate Data Portal and completes a long-standing gap in NCEI's ability to characterize the State of the Climate for all 50 states. NCEI maintains monthly statewide, divisional, and gridded average temperature, maximum temperatures (highs), minimum temperature (lows) and precipitation data for Hawaii over the period 1991-2025.

The National Ocean Service (NOS) maintains a long-term database containing data from active and historic stations installed all over the United States and U.S. territories. Since the 1990s, NOAA's Center for Operational Oceanographic Products and Services (CO-OPS) has been collecting various meteorological data along the U.S. coastline, around the Great Lakes and connecting channels, as well a...

The Mariners Weather Log (MWL) is a publication containing articles, news and information about marine weather events and phenomena, worldwide environmental impact concerns, climatology studies, storms at sea, and weather forecasting. The MWL is dedicated to the NWS Voluntary Observing Ship (VOS) Program, Port Meteorological Officers (PMOs), cooperating ships officers, and their vessels. Through the various articles, mariners and other interested individuals are kept abreast of the most current operational uses of marine weather and oceanographic data. There are also articles concerning general meteorology and oceanography. The marine weather review included in the magazine contains a smooth log and sometimes a rough log. The smooth log (complete with cyclone tracks, climatological data from U.S. Ocean Weather Station "Hotel" and buoys, and gale and wave tables) is a definitive report on normal monthly weather systems, the primary storms that affected marine areas, and ship casualties for recent months. The rough log, when published, is a preliminary account of the weather for recent months that are not covered in the smooth log. Also included in the magazine is a special hurricane section as well as a section dealing with current projects and relevant scientific/meteorological occurrences. The archive holds a subset of these publications.

The Global Hourly Summaries are simple indicators of observational normals which include climatic data summarizations and frequency distributions. These typically are statistical analyses of station data over 5-, 10-, 20-, 30-year or longer time periods. In a GIS map service, the results of these calculations are represented by a given symbology set for different statistical criteria and observation type. Having the ability to modify the symbology "on-the-fly" is a useful tool in the analysis of station trends, accuracy, and regional or localized variances. The summaries are computed from the global surface hourly dataset. This dataset totaling over 350 gigabytes is comprised of 40 different types of weather observations with 20,000 stations worldwide. NCDC and the U.S. Navy have developed these value added products in the form of hourly summaries from many of these observations. These data are a subset of the Integrated Surface Hourly dataset (DSI-3505) (C00532).

The Surface Weather Observation Collection consists primarily of hourly, synoptic, daily, and monthly forms submitted to the archive by the National Weather Service (formerly the U.S. Weather Bureau). Other groups, including the U.S. military and local and state governments have also submitted surface weather observations that are part of this collection. All data within the collection consist of tabulated observations at designated land stations. Observations usually include temperature, precipitation, sky conditions, pressure, and other atmospheric phenomena.

Subsets of the collection have been scanned and made available as digital images upon request (see associated resources). These subsets are generally broken down into finer time scale (for example, monthly vs hourly observations) or by a specific time period (for example, pre-1948).

Hourly Precipitation Data (HPD) is digital data set DSI-3240, archived at the National Climatic Data Center (NCDC). The primary source of data for this file is approximately 5,500 US National Weather Service (NWS), Federal Aviation Administration (FAA), and cooperative observer stations in the United States of America, Puerto Rico, the US Virgin Islands, and various Pacific Islands. The earliest data dates vary considerably by state and region: Maine, Pennsylvania, and Texas have data since 1900. The western Pacific region that includes Guam, American Samoa, Marshall Islands, Micronesia, and Palau have data since 1978. Other states and regions have earliest dates between those extremes. The latest data in all states and regions is from the present day. The major parameter in DSI-3240 is precipitation amounts, which are measurements of hourly or daily precipitation accumulation. Accumulation was for longer periods of time if for any reason the rain gauge was out of service or no observer was present. DSI 3240_01 contains data grouped by state; DSI 3240_02 contains data grouped by year.

Several different government offices have published the Daily weather maps over its history. The publication has also gone by different names over time. The U.S. Signal Office began publication of the maps as the War Department maps on Jan. 1, 1871. When the government transferred control of the weather service to the newly-created Weather Bureau in 1891 the title changed to the Department of Agriculture weather map. In 1913 the title became simply Daily weather map. Eventually, in 1969, the Weather Bureau began publishing a weekly compilation of the daily maps with the title Daily weather maps (Weekly series). The the principal charts are the Surface Weather Map, the 500 Millibar Height Contours Chart, the Highest and Lowest Temperatures chart and the Precipitation Areas and Amounts chart. This library contains a very small subset of this series: 11Sep1928-31Dec1928, 01Jan1959-30Jun1959, and 06Jan1997-04Jan1998.

Mexican Surface Daily Observations taken at 94 observatories located throughout Mexico, beginning in 1872 and going up through 1981. The data resided on paper records stored in non-climate-controlled conditions, and were therefore subject to deterioration and loss. This Climate Dabase Modernization Program task set up digital cameras to image these records, creating color .jpg images of the Mexican National Meteorological Service forms.

The 14th Weather Squadron of the U.S. Air Force (USAF-14WS) creates a comprehensive dataset of weather observations; these observations stem from hundreds of domestic and international networks on a daily basis. Observations cover a broad spectrum of information that are incorporated into the NOAA Integrated Surface Data product. This dataset includes: cloud height and quality observations; extreme temperature; wind observations; ocean observations covering temperature, salinity, current speed and direction, waves, ice data; visibility; air temperature; precipitation; snow depth; atmospheric pressure; station metadata; etc. Up-to-date station metadata is included with every data submission, though not all stations described are included with every data submission. This is one of the primary source feeds into the NOAA Integrated Surface Data product.

This dataset includes one-minute observations for precipitation type and amount, station pressure, temperature, dew point temperature, lightning detection elements, and the Frozen Precipitation Sensor Frequency for approximately 900 stations in the U.S., Puerto Rico, the U.S. Virgin Islands, and some Pacific island territories as part of the Automated Surface Observing Systems (ASOS) network. The ASOS Program is a joint effort of the National Weather Service (NWS), the Federal Aviation Administration (FAA), and the Department of Defense (DOD). The ASOS network was designed to support weather forecast activities and aviation operations and, at the same time, support the needs of the meteorological, hydrological, and climatological research communities. The ASOS 1-minute page 1 and page 2 data were collected and processed by the NOAA National Centers for Environmental Information (NCEI).

METAR is the international standard code format for hourly surface weather observations. The acronym roughly translates from French as Aviation Routine Weather Report. Because METAR data is collected for aviation purposes, observation stations are located at airports and helipads. This dataset shows locations of the stations with the URL attribute that allows linkage to the most recent observations.

Diaries and Journals containing weather information in a non-tabular format. Records date from 1735 through the early 20th century. Much of the weather and climate data recorded by the founding fathers of this country (Washington, Jefferson and Franklin to name a few) were archived in original manuscripts, then microfilmed and stored at the National Archive and Records Administration (NARA). Those records available from NARA on microfilm have been imaged and placed on the EV2 system. To date, there are more than 42 million of those images on-line. These colonial diaries and data are a treasure trove to the climatologist seeking data on climate of the 19th century.