Continental United States
Spatial Resolution
Data Source(s)
Science Partner


GridMET is a gridded meteorological dataset of multiple climate variables on a daily time scale across the United States. It is a hybrid of the National Land Data Assimilation System (NLDAS) (Mitchell et al., 2004) and the Parameter‐Elevation Regressions on Independent Slopes Model (PRISM) datasets (Daly, 2006).


ASCE Grass Reference Evapotranspiration (ETo): Penman-Monteith reference ET based on a grass reference crop defined by American Society of Civil Engineers (Allen et al., 2005)

ASCE Alfalfa Reference Evapotranspiration (ETr): Penman Monteith reference ET based on a alfalfa reference crop defined by American Society of Civil Engineers (Allen et al., 2005)

Precipitation (PPT): Daily precipitation

Potential Water Deficit (PPT-ETo): Difference between total precipitation and total ETo over specified time interval

Min Rel. Humidity: Daily minimum relative humidity (%)

Max Rel. Humidity: Daily maximum relative humidity (%)

Specific Humidity: The ratio of the mass of water vapor to the total mass of air for a unit volume (kg/kg)

Downward Shortwave Radiation: At surface daily average shortwave radiation (W/m^2)

Mean Temperature: Mean daily temperature

Min Temperature: Minimum daily temperature

Max Temperature: Maximum daily temperature

Vapor Pressure Deficit: Mean daily vapor pressure deficit (kPa)

Wind Speed: Mean daily wind speed at 2m height

Burning Index: Measure of fire intensity and related to the effort of containing a fire (NFDRS)

Energy Release Component (ERC): Index of large fire potential and component of the United States Forest Service National Fire Danger Rating System (Deeming et al.,1978)

100-HR Dead Fuel Moisture (FM-100): Moisture level of dead fuels within the 1-3 inch diameter class (%)

1000-HR Dead Fuel Moisture (FM-1000): Moisture level of dead fuels within the 3-8 inch diameter class (%)

Palmer Drought Severity Index (PDSI): A ~9 month timescale drought index based on precipitation and ASCE grass reference evapotranspiration (ETo) (Palmer 1965)

Evap. Demand Drought Index (EDDI): A multi-timescale drought index based on evaporative demand of the atmosphere (Hobbins et al., 2016; McEvoy et al., 2016)

Standard Precipitation Index (SPI): A multi-timescale drought drought index based on precipitation (McKee 1993)

Standard Precipitation Evaporation Index (SPEI): A multi-timescale drought index based on precipitation minus ASCE grass reference evapotranspiration (ETo) (Vicente-Serrano 2010)

Technical Information

Continental United States
Period of Record
Spatial Resolution
Temporal Resolution
Daily (updated every day)
Data Summaries
max, min, mean, median, anomalies, trend and statistical significance, spatial and temporal aggregations, time series, standardized indices
Data Source(s)
Data Formats
raster (geotiff), raster tile (tile ID), time series (.csv, .xls, .json, .geojson)

Abatzoglou, J. T. (2013). Development of gridded surface meteorological data for ecological applications and modelling. International Journal of Climatology, 33(1), 121-131.

Allen, T. G., I. A. Walter, R. Elliot, and T. A. Howell (2005), ASCE-EWRI Standardization of Reference Evapotranspiration, Am. Soc. Civ. Eng. Water Int.

Daly, C., Halbleib, M., Smith, J.I., Gibson, W.P., Doggett, M.K., Taylor, G.H., Curtis, J., and Pasteris, P.A. 2008. Physiographically-sensitive mapping of temperature and precipitation across the conterminous United States. International Journal of Climatology, 28: 2031-2064

Deeming JE, Burgan RE, Cohen JD. 1978. The National Fire‐Danger Rating System—1978. Revisions to the 1978 National Fire‐Danger Rating System. General Technical Report INT‐39. Ogden, UT: US Department of Agriculture, Forest Service, Intermountain Forest and Range Experiment Station; 63.

Hobbins, M. T., Wood, A., McEvoy, D. J., Huntington, J. L., Morton, C., Anderson, M., & Hain, C. (2016). The evaporative demand drought index. Part I: Linking drought evolution to variations in evaporative demand. Journal of Hydrometeorology, 17(6), 1745-1761.

McEvoy, D. J., Huntington, J. L., Hobbins, M. T., Wood, A., Morton, C., Anderson, M., & Hain, C. (2016). The evaporative demand drought index. Part II: CONUS-wide assessment against common drought indicators. Journal of Hydrometeorology, 17(6), 1763-1779.

McKee, T. B., N. J. Doesken, and J. Kliest, 1993: The relationship of drought frequency and duration to time scales. In Proceedings of the 8th Conference of Applied Climatology, 17-22 January, Anaheim, CA. American Meteorological Society, Boston, MA. 179-184.

Mitchell, K.E., Lohmann, D., Houser, P.R., Wood, E.F., Schaake, J.C., Robock, A., et al. (2004). The multi-institution North American Land Data Assimilation System (NLDAS): Utilizing multiple GCIP products and partners in a continental distributed hydrological modeling system. Journal of Geophysical Research D: Atmospheres, 109, 1–32.

NFDRS System Inputs and Outputs (Accessed 8/6/2020),in%20feet%20multiplied%20by%20ten.

Palmer, W. C. (1965). Meteorological drought (Vol. 30). US Department of Commerce, Weather Bureau.

Vicente-Serrano S.M., Santiago Beguería, Juan I. López-Moreno, (2010) A Multi-scalar drought index sensitive to global warming: The Standardized Precipitation Evapotranspiration Index – SPEI. Journal of Climate 23: 1696-1718.

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