Weather Data File Types
Representation and storage of short-term weather data have evolved along with the computer and information revolution of the last 40 years. This page summarizes different data sets and file formats of weather data.
Data sets of weather data
The table below lists typical year weather data available on the internet. Most data sets can be downloaded from DOE2.com.
|Data Set||Full Name||Derived from||Covered Locations|
|CTMY||Canadian TMY||Canadian Government data||12 Canadian locations|
|CTMY2||Canadian TMY 2||Canadian Government data||40 Canadian locations|
|CTZ2||California Thermal Zones 2||Supplied by the California Energy Commission in 1992||16 California zones|
|GBRI||GRIdded Binary||Standardized by the World Meteorological Organization to store historical and forecast weather data|
|TMY||Typical Meteorological Year||US NOAA NCDC data sets||238 US locations|
|TMY2||Typical Meteorological Year 2||US DOE NREL data sets||238 US locations|
|TMY3||Typical Meteorological Year 3||US DOE NREL datasets||1,200 US locations|
|TRY||Test Reference Years||US NOAA NCDC data sets||60 US locations|
|IWEC||International Weather for Energy Calculations||US NOAA NCDC data sets||227 locations outside the USA and Canada|
|WYEC||ASHRAE Weather Year for Energy Calculations||US NOAA NCDC data sets||51 US locations|
|WYEC2||ASHRAE Weather Year for Energy Calculations||US NOAA NCDC data sets||51 US locations|
Typical Meteorological Year (TMY) weather data
A Typical meteorological year (TMY) is a collation of selected weather data for a specific location, generated from a data bank much longer than a year in duration. It is specially selected so that it presents the range of weather phenomena for the location in question, while still giving annual averages that are consistent with the long-term averages for the location in question. The latest TMY weather data sets, TMY3, are data sets of hourly values of solar radiation and meteorological elements for a 1-year period. Their intended use is for computer simulations of solar energy conversion systems and building systems to facilitate performance comparisons of different system types, configurations, and locations in the United States and its territories. Because they represent typical rather than extreme conditions, they are not suited for designing systems to meet the worst-case conditions occurring at a location. The source data are available for download from the National Solar Radiation Data Base.
File formats of weather data
Early automated data formats of weather data replicated punched card layouts formerly used for data entry by weather services. To save transcription cost, often data from only every third hour were made available. High cost, inconvenient formats, and omitted data made for difficult application to simulation. Until recently, sources files of weather data typically consist of 8,760 fixed format records (values located in specific columns of each data line). Current formats, such as TMY3 and EPW, are now more compatible with desktop spreadsheet tools. They are comma-separated and include metadata (such as site location) and column headings that make them somewhat self-documenting.
|.EPW||EnergyPlus weather files||EnergyPlus, ESP-r||EnergyPlus|
|.DDY||ASHRAE Design Conditions Design Day Data file||EnergyPlus|
|.BIN||Binary data||eQUEST, DOE-2||DOE2.com Whitebox|
|.STAT||Summary report||Directly read from Notepad||EnergyPlus|
|.CSV||Spreadsheet data for TMY3 files||Spreadsheet-based and home-coded tools||NREL|
|.WEA||Weather Tool data originally developed by Autodesk for Ecotect||Ecotect, Weather Tool||Install Ecotect|
|.TMY2||TMY2 data in ASCII format||TRNSYS||NREL|
Weather file format conversion
- EnergyPlus Weather Statistics and Conversions: A utility in the EnergyPlus installation package
- TMY3toTMY2: A utility developed by NREL
- eQ_WthProc: Convert EnergyPlus EPW Files into eQUEST and DOE-2 BIN Files
- DOEWth: Convert NOAA/NCDC and Other Common Format Files into eQUEST and DOE-2 BIN Files
- .xls to .bin
 C. S. Barnaby and D. B. Crawley, "Weather data for building performance simulation," in Building Performance Simulation for Design and Operation, J. L. M. Hensen and R. Lamberts, Eds., ed Oxford: Spon Press, 2011.
 IWEC, Building Energy Software Tools Directory, available at: http://apps1.eere.energy.gov/buildings/tools_directory/software.cfm/ID=369/pagename=alpha_list
 Weather Data & Weather Data Processing Utility Programs, DOE2.com, available at: http://doe2.com/index_wth.html
 National Solar Radiation Data Base, 1991- 2005 Update: Typical Meteorological Year 3, available at: http://rredc.nrel.gov/solar/old_data/nsrdb/1991-2005/tmy3/
 World Meteorological Organization, A GUIDE TO THE CODE FORM FM 92-IX Ext. GRIB, available at: http://www.wmo.int/pages/prog/www/WDM/Guides/Guide-binary-2.html