Daymet is a gridded data set of estimates of daily weather parameters for North America. Available weather parameters include daily continuous surfaces of minimum and maximum temperature, precipitation occurrence and amount, humidity, and shortwave radiation.
The daily time step, 1 km x 1 km spatial resolution, and North American spatial extent of the data set makes it a unique and valuable contribution to scientific, research, and educational communities.
These data are generated by a collection of software and algorithms that interpolate and extrapolate from daily meteorological observations and a Digital Elevation Model (DEM). The Daymet data set has been broadly applied over a wide variety of scientific and research fields including hydrology, terrestrial vegetation growth models, carbon cycle science, and regional to continental climate change analyses.
Access to the Daymet data set is available through various tools and formats allowing a rich resource of daily surface meteorology to students, educators, and the research community.
Available daily gridded variables:
- Minimum temperature (degrees C)
- Maximum temperature (degrees C)
- Precipitation (mm/day)
- Humidity as water vapor pressure (Pa)
- Shortwave Radiation (W/m^2)
- Snow water equivalent (kg/m^2)
- Daylength (s)
- Resolution is 1 km x 1 km
- Extent is North America and Hawaii, including Canada, Mexico, the United States of America including Alaska, Puerto Rico, and Bermuda.
- Lambert Conformal Conic Projection
- Data are a daily timestep.
- Data start in 1980 and extend through the most recent full calendar year.
Data Access and File Formats
- Single Pixel Extraction Tool - ASCII output file with all (or a sub-set of) parameters for a selected pixel
- THREDDS Data Server - netCDF gridded files for individual Daymet parameters
- Daymet Tile Selection Tool - netCDF gridded files by Daymet tile for individual Daymet parameters
- Climatological Summaries - Monthly Climate Summary files in geoTIFF file format for all parameters
Get Daymet Data
Find and order data sets:
- See list of data sets and download data
- Retrieve Daymet data by HTTP browse
- Search Daymet data (Mercury)
Input requirements for the Daymet model include a digital elevation model and daily observations of maximum and minimum temperature, and precipitation from ground-based weather stations. The Daymet method is based on the spatial convolution of a truncated Gaussian weighting filter with the set of station locations. Sensitivity to the typical heterogeneous distribution of stations in complex terrain is accomplished with an interactive station density algorithm. In the Daymet algorithm, spatially and temporally explicit analysis of the relationships of temperature and precipitation to elevation are performed. Surfaces of humidity (as water vapor pressure) are generated as a function of the predicted daily minimum temperature and predicted daily daylight temperature. Incident solar radiation is estimated as a function of sun-slope geometry and interpolated diurnal temperature range.
The following Daymet resources are maintained by the ORNL DAAC:
- Daymet Project Web Site
- Daymet Mailing List
- Daymet Bibliography
- Daymet Scripts, Tools, and How-To's
- Daymet User's Guides and Documentation
- Daymet Web Services Guides
- To cite Daymet data, follow these citation examples.